CONVERT DEGREES TO PRISM DIOPTERS IN STRABISMUS
Ramiro Alvarez Clavero
I would like to know how to convert degrees to prism diopters and
viceversa.
Is there any newsgroup specifically for strabismus?
Thanks someone answering this questions.
Ramiro Alvarez
ra...@arrakis.es
Mike Tyner, OD
Ramiro Alvarez Clavero wrote:
>
> I would like to know how to convert degrees to prism diopters and
> viceversa.
Prism diopters are a convenient approximation that works best
around zero.
Textbook definition: One prism diopter deviates an image at
one meter away by one centimeter.
So one prism diopter = arctan(1/100), but only at zero.
--
Mike Tyner, OD
drm...@bham.com
al
Ramiro Alvarez Clavero wrote:
>I would like to know how to convert degrees to prism diopters and
>viceversa.
About two prisms per degree, depending on the corrective glasses in front of
the eyes. There are nomograms in books on strabismus how to change degrees
to prisms and vice versa.
>Is there any newsgroup specifically for strabismus?
No.
Cheers, Al
Ales Tilen, MD, Ophthalmologist
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
.............
>
>Prism diopters are a convenient approximation that works best
>around zero.
>
>Textbook definition: One prism diopter deviates an image at
>one meter away by one centimeter.
>
>So one prism diopter = arctan(1/100), but only at zero.
Well, if you always measure the deviation at right angles to the
distance dimension, there's no "approximation" and "only at zero" is
not required? If this takes the image out of focus, because the
hypotenuse of the triangle has enlarged too much beyond the
reference-datum normal distance,that only shows how stupid it was for
optoms not to simply stick to speaking of the angle of deviation in
degrees, radians or whatever, like everyone else, instead of rounding
up some esoteric term (which confuses with *non*-prism 'diopters')
behind which to practice their witchcraft. They really should've
tried to pass their high-school math classes instead. If you claim
the arctan definition holds only at zero, how would you define 'prism
diopter' as used to measure deflection to some considerable angle away
from zero?
Ray
The ratio comes out roughly 2 diopters/degree.
Mike Tyner, OD
Raymond A. Chamberlin wrote:
>
> reference-datum normal distance,that only shows how stupid it was for
> optoms not to simply stick to speaking of the angle of deviation in
> degrees, radians or whatever, like everyone else, instead of rounding
> up some esoteric term (which confuses with *non*-prism 'diopters')
> behind which to practice their witchcraft. They really should've
> tried to pass their high-school math classes instead.
I know you aren't interested in facts that oppose your personal conspiracy
theories, but I don't believe this definition was written by an O.D.
Don Johnson
On Thu, 20 Nov 1997 09:41:14 GMT, ra...@sirius.com (Raymond A.
Chamberlin) wrote:
>...optoms not to simply stick to speaking of the angle of deviation in
>degrees, radians or whatever, like everyone else, instead of rounding
>up some esoteric term (which confuses with *non*-prism 'diopters')
>behind which to practice their witchcraft. They really should've
>tried to pass their high-school math classes instead. If you claim
>the arctan definition holds only at zero, how would you define 'prism
>diopter' as used to measure deflection to some considerable angle away
>from zero?
>
>Ray
>
>The ratio comes out roughly 2 diopters/degree.
Mr. Chamberlin,
I see your name attached to every posting that has to do with
converting diopter numbers to something else, usually to vision by the
20/20 method. I have astigmatism which means that my correction
(diopters) may be mild, but without astigmatism correction I still
can't see the "mathematical" value suggested by my needed diopters.
There may be some mathematical relationship, but what is the point
when none of us can use these numbers? Eye doctors use a machine to
adjust out as much as they can, both diopters and astigmatism, to
prescribe the glasses. No doctor would prescribe glasses from an eye
chart exam, because of the other factors.
It would be nice if we could just leave this alone for a while.
Don Johnson
djohnson@*Surfari.Net
For all you automated e-mail spammers,
the Federal Communications Commission:
Chairman Reed Hundt: rhu...@fcc.gov
Commissioner James Quello: jqu...@fcc.gov
Commissioner Susan Ness: sn...@fcc.gov
Commissioner Rachelle Chong: rch...@fcc.gov
Specs31
)>It would be nice if we could just leave this alone for a while.
>
>Don Johnson
>djohnson@*Surfari.Net
the COS squared of the angle times the prism = horz. prism (180)
the SIN squared of the angle times the prism = vert. prism (090
try playing with this formula for awhile and see if it improves your
coverting actual prism diopters into a refrence point ....
you would be supplied an axis but try converting it inot a actual number
that is understandable.... like saying 3 base in and 2 up...etc ......and by
the way thier are two methods one based on a 360 degree layout amd one on 180
degree's so besides figuring the spherical for distant and the cylindrical for
astigmatic corrction and the axis it falls on now you have to find out the axi
direction and amount in base in /out and base up/down and convert that to
diopters in prism.....just a thought i would throw out there.(..from your local
shoe salesman......)hee hee
hey and for the OD that just hates me to tears (according to Ray.... you
know the one that considers me a optical ninny...ha ha ha ha ha ha h ah a ha ha
ha ha ha ha ha ha ) sometimes us lab rats know more than you think when it
comes to optics
theory is nice...if you are bored and nothing is going on...than have at
it.........
Ta,
Jeff
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
................
>
I don't believe this definition was written by an O.D.
>
I'm not sure of your point. Are you saying an OD would've written a
better one? You're and OD; why don't you post *your* definition here
if you think the one you took from a textbook isn't sufficient?
Ray
Raymond A. Chamberlin
djoh...@Surfari.net (Don Johnson) wrote:
>
................
>
>I see your name attached to every posting that has to do with
>converting diopter numbers to something else, usually to vision by the
>20/20 method. I have astigmatism which means that my correction
>(diopters) may be mild, but without astigmatism correction I still
>can't see the "mathematical" value suggested by my needed diopters.
This appears too garbled for me to be sure what is being said. Are
you saying that your spherical correction is small but your
cylindrical correction is significant, and that therefore, in your
case, any formula we propose relating spherical correction to Snellen
acuity is of little value in your case? If this is not what you are
trying to say, state more clearly what it is that you *are* trying to
say.
>There may be some mathematical relationship, but what is the point
>when none of us can use these numbers?
Why is it, do you think, that disparate, uncommunicating people keep
posting to this NG asking this question? Do you think they are all a
bunch of blithering idiots and the optoms who keep denying there is
any relationship between manifested error in ocular focal length and
Snellen-scale degradation in resolution acuity are all holy wisemen?
They ask because (maybe unlike you) they have good horse sense and
that someone -- a secretive OD, a DMV, a school nurse, whatever -- has
given them a '20/xx' number as a measure of how good their vision is,
but has not given them any idea of what prescription of eyeglasses or
contact lenses they will need in order to permit them to see as best
corrected or nearly so -- or else, vice versa, they have the
prescription but haven't been told, or have forgotten, their Snellen
acuity measure and want to compare it to that of others or for
whatever other reason.
>Eye doctors use a machine to
>adjust out as much as they can, both diopters and astigmatism, to
>prescribe the glasses.
"Both diopters and astigmatism." What does that mean? Both spherical
and cylindrical (regular astigmatic) dioptric error are measured in
diopters (units of the reciprocal of the difference in the reciprocals
of the actual and the correct focal lengths for imaging on the
retina). Of course those who refract do that.
>No doctor would prescribe glasses from an eye
>chart exam, because of the other factors.
The purpose of this conversion is certainly not to produce a
prescription for making eyeglasses or contact lenses from a
Snellen-chart test.
>It would be nice if we could just leave this alone for a while.
You got a problem, Cousin? I'm certainly not going to post on this
subject from out of the blue, but each time some independent person --
naively in respect to the optometric mystique baloney involved in it,
but legitimately in terms of sensing that there *is* such a
relationship and feeling some value in relating the two measures in
order to have a good overall view of what goes on with the apolitical
aspect of eyes and vision correction -- poses this question in this
newsgroup, I'm going to respond with the straightforward empirical
facts and science involved. It is up to *them* what they want to do
with this knowledge. Anyone in your position -- who feels that, in
his/her particular situation, this universal relationship of empirical
reality and physics is of no value to him/her -- is quite welcome to
go on to the next post.
I happen to like this issue with ophthalmic types, because every time
they come on and say, "There is no relationship between 20/xx and
diopters," it points up their exclusive inhouse isolation from the
real world and optical science, and shows clearly the little esoteric
games they keep playing in order to propel an expensive service
commodity, along with their person-service-fed egos, in the face of
the cheapening effect that scientific understanding imposes on
free-market commerce. In the case of eyeglasses, science, and its
acceptance by the public in place of ritual and special-interest law,
can replace expensive personal services with inexpensive automated
services and mass-produced devices. The Internet is a place for free
information as well as commerce; in fact, that was its original
purpose. It readily allows correction of any such information that is
wrong. Simple statements here, by persons putting 'OD' or 'MD' after
their names, to the effect that such aspects of the reality of
inanimate physics don't apply to what they do by the grace of Snellen
or whomever are not going to stand up too well. And their fans, who
boo anything not supporting their heros, can take a flying leap.
Ray
Raymond A. Chamberlin
djoh...@Surfari.net (Don Johnson) wrote:
>
................
>
>I see your name attached to every posting that has to do with
>converting diopter numbers to something else, usually to vision by the
>20/20 method.
Sorry, but the above got me onto the wrong topic for this post. . .I
just noticed. That just shows how the optometric idiocy of using the
word 'diopter' for two entirely different things can contaminate
almost anything.
>
.................
>
Ray
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
I guess it was expected that I not be able to make anything out of
that. hoo hoo TM.
Ray
Mike Tyner, OD
> I don't believe this definition was written by an O.D.
>
> I'm not sure of your point. Are you saying an OD would've written a
> better one? You're and OD; why don't you post *your* definition here
> if you think the one you took from a textbook isn't sufficient?
>
You railed at optometry for defining prism diopters in such screwy terms.
I don't think optometry wrote the definition.
Mike Tyner, OD
Raymond A. Chamberlin wrote:
>
> >I see your name attached to every posting that has to do with
> >converting diopter numbers to something else, usually to vision by the
> >20/20 method.
>
> Sorry, but the above got me onto the wrong topic for this post. . .I
> just noticed. That just shows how the optometric idiocy of using the
> word 'diopter' for two entirely different things can contaminate
> almost anything.
Why is this "optometric idiocy?" Optometrists didn't define it,
and ophthalmology and opticianry both use the term "prism diopter."
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>> I don't believe this definition was written by an O.D.
>> Raymond A. Chamberlin wrote:
>>
>> I'm not sure of your point. Are you saying an OD would've written a
>> better one? You're and OD; why don't you post *your* definition here
>> if you think the one you took from a textbook isn't sufficient?
>>
>
>You railed at optometry for defining prism diopters in such screwy terms.
>I don't think optometry wrote the definition.
Who do you think did? Of course, I'd rather know who you *know* did.
At the very least, tell me *why* you think optometry didn't? ;-) Do
you think optical physicists did?
Ray
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
...............
>
>Why is this "optometric idiocy?"
Because diopters and prism diopters don't even have the same
dimensions. Diopters are simply reciprocal meters and prism diopters
aren't *anything* -- the number associated with them is a pure number
measuring an angle (or the arctangent of one) -- where they should've
simply stuck to degrees/minutes/seconds (or radians).
>Optometrists didn't define it,
So who did and what's your authority?
>and ophthalmology and opticianry both use the term "prism diopter."
Can't I put all three of these in the same institutional cell. OK, so
they tend to scrap a little; we got bandages.
Ray
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
..........
>
>Why is this "optometric idiocy?"
And it's got Don Johnson confused between two different issues -- and
me, because I forgot to read the title of the thread and relied on his
confusion. (And when I get confused, you know somebody else has to
have been an idiot. ;-) )
Ray
Dr. P. Rozanec
On Tue, 25 Nov 1997 08:28:43 GMT, ra...@sirius.com (Raymond A.
Chamberlin) wrote:
>
>Sorry, but the above got me onto the wrong topic for this post. . .I
>just noticed. That just shows how the optometric idiocy of using the
>word 'diopter' for two entirely different things can contaminate
>almost anything.
>
Ray,
There's no patent on knowledge. So why don't you go out and get
some??
Your thinly-veiled vendetta, bordering on slander is showing through
again. Please stop wasting bandwidth, and post more constructively.
Thanks.
Peter
-------------------
NOTE:
To avoid spammers,
Please take out 'nospam.net' in my address listed above and replace it with 'ica.net'
VernonH
>> Raymond A. Chamberlin wrote:
>
> I'm not sure of your point. Are you
>saying an OD would've written a
> better one? You're and OD; why don't you
>post *your* definition here
> if you think the one you took from a textbook
>isn't sufficient?
>
Listees
Against my better judgement I am adding my 2 cents.
Probably the term prism "diopter" was a bad choice.
The 3 Os generally just say "3 base down", or "5 base at 135" etc. We
frequently use the delta letter for "prism diopter"
The concept works well to determine the amount of prism power BECAUSE the
darn target screen is FLAT. Remember the definition is 1 unit at a distance of
100 units. This takes care of the FLAT testing screen and the whole wall may be
involved. The lensometer with its FLAT reticule is used in the layout for
edging a lens so that the correct areas of the lens end up where they belong.
Prisms are seldom over 5D.
Both OMDs and ODs and Opticians use prism diopters. Degrees are used in
calculations for
strabismus surgery. And also with some measuring and/or orthoptic (training)
instruments that pivot
around the eye. Generally dealing with large amounts there.
Also the famous Prentice's Rule. Prism power = Lens Power X Distance from
optical center of the lens in cm.
And back in the days of glass (and before computerization) grinding 1 mm more
thickness on one
side of a 50mm blank than the opposite side equaled one prism diopter.
Remember the prism diopter concept works because we measure, manufacture, and
inspect using the same concept. Can't very easily measure in degrees. And we
are working with thin lenses and small amounts of prism. IT WORKS!!
Now when I wrote a computer lens surfacing program for my lab (back before any
programs were available commercially) I had to hunt up my old geometry and trig
books. There I had to deal with degrees and radians etc. The real nightmare was
keeping the algebraic signs straight for Rt & LT lenses and the calculations
for sphero-cylindrical lenses. The frame shape and size (in many meridians)
measurements have to also be known. But I have wandered as usual.
Below is apart of a table from my friend Troy Fannin's book Clinical Optics.
First 1 degree=0.00175 radian=1.75 centrads
Degrees Centrads Prism Diopters %Error (in assuming
Prism Diopters=centrads)
10 17.45 17.63 -0.1
15 26.18 26.79 -0.8
20 34.90 36.40 -1.4
etc etc etc
57.3 100.00 155.76 -55.8
_____________________________________________________
Remember we seldom prescribe over a couple prism diopters.
Most prism calculations made in the labs is amount of prism needed to be ground
into a lens to move
the optical center of the lens so it will end up in the frame in the proper
place with relation to the eye.
MORE
If a 5.00 Diopter lens (plus or minus) is placed in front of the eye with its
optic center 4 mm from the center of the optic axis of the eye there will be 2
diopters of PRISM power induced. (Prentice's
formula --- Refracting power x displacement in CM = prism power thus 5 x 0.4=2
prism diopters
So if after cataract surgery one eye only you may have an Rx Rt 0.00 and LT
+4.00.
So (if lenses are placed correctly in frame) if you look away from anything
straight ahead say a half
inch from center of lenses you will have no prism effect with the RT lens but
(1/2" = about 13mm)
4 x 1.3CM= 5.2 diopters of prism imbalance. You will see double (if the left
eye can see)
Besides there are all kinds of other devils at work such as the magnification
that travels with a
+4.00 lens and things should also appear curved in a wierd way etc etc.
Wife says turkey is waiting. Happy Thanksgiving to all.
Vernon, optometrist for over 45 yrs
Ohio State '52
Sorry I don't have a chance to proof read. I can delete flames but the wife is
something else. :-))
Specs31
>That just shows how the optometric idiocy of using the
>> word 'diopter' for two entirely different things can contaminate
>> almost anything.
>
>and ophthalmology and opticianry both use the term "prism diopter."
Ray,
using the word "diopter" after a rx power or a prescribed amount of prism
is not two entirely different things...
when dealing in focal power and corrective power (prism) than it is
measured in terms of diopters...and degree's ... say you had a +1 OU with
prescribed prism 2 BO/ou ....than when i would be talking about that lens it
would be phrased as" 1 D WITH 2D base out".... when dealing in prismatic lens
you can get it one of two ways....with the prescribed prism in diopters or
OD/OMD will give you the power in diopters and give you the prism in degrees
and you have to convert that degree's of prim into a number that is
transferable.....when checking any RX the lensometer is based on three
things...power,axis and prismatic diopters....
when you look into a lensometer will see those three things...one solid
line for cylinder (astigmatic correction) three smaller lines at a 90 degree
angle for spherical correction...and than rings that are set for measuring
distence in prism diopters....
where the two lines cross (spherical,cylindrical) is the optical
center...and where they fall at on those rings is the amount of prismatic
effect you want or need.......or if done incorrectly you don't want or need....
same as using prentice law for finding the amount of induced prism if
the pupilary distence is not correct. i can calculate it all out or just check
it in a lensometer
someone comes in with a pair of lens ..they wear a pd of 63 but when i
check the lens i would put them in the lensometer and move the lens till the
two sets of lines cross dead center of the rings...than dot it up...next just
measure that distence between those two dots and compare it to the pd needed
and than you know if it is a induced prism problem....than measure out the
needed pd and put it back in the lensometer and than see where the two sets
cross.....if it is outside of that center than you know it is incorrect ....you
have dead center and than a half diopter ring and 1 diopter on out (2,3
.....etc etc)
its very easy to plot out ...
in the industry most of the time when you talk about power they just say
if it is + or - ...and prism is just referred to as base out/up or base in/out
... even though the word diopter is used after those two things you just don't
use the word that much....
same as any industry you have key words that have a wide variety of uses
and attachments but you tend to drop that word when talking to someone in the
same industry because its a given that you each know it already... as in the
example i used (+1sph. OU/2BO) when a optician or OD or OMD is talking to me
s/he isn't going to say +1 diopter with 2 diopters base out... why would they??
thats a given to a fellow optical person??
you can nick pick , slash and burn any industry if you try to use every
term and word when ever you think it should be used as a layman looking in from
the outside.... i can give plenty of examples in the optical industry where
words are used that we all know the meaning but translated to a layman the seem
contradictive... take power... when talking about power in lens in the industry
you would say its in quaters or twelths... even though you know its not
exact... but you know that when dealing with a power below a quater is not
really effecting much of anything...on paper if you work out the mathmatics it
may look like a large number but translated into how it effects visual acuity??
its nothing...
its the same in industry and i'm sure you could probably rattle off a
few yourself that you used that to an outsider may have looked contradictory or
even way off base but to another person that does the same thing you do it
looked ordinary.....
hope everyone gets enough gobbler and no upset tummy's
Quote for the day:"I didn't fight my way to the top of the food chain to be
a vegetarian."
Ta,
Jeff (still not a OD/OMD...but will take a #1 from mickey D's )
Mike Tyner, OD
In Yet Another Worthwhile Post, Ray Chamberlin seized the opportunity to say:
>
> Some day I'm going to print a study of the types of people who use
> terms like 'thinly-veiled threat" (or in this case, '. . .vendetta')
> and 'bordering on slander'.
Be sure to include those who use "Mickey Mouse" and "don't know what
the hell they're talking about. "
> Meanwhile, let it be said that those who duck like a quack. . .
That's the nice thing about newsgroups, isn't it? You can say anything
you like; whatever pops into your head. Everyone has the benefit of
your point of view.
Raymond A. Chamberlin
eye...@nospam.net (Dr. P. Rozanec) wrote:
>
.........
>
>Your thinly-veiled vendetta, bordering on slander is showing through
>again. Please stop wasting bandwidth, and post more constructively.
Some day I'm going to print a study of the types of people who use
terms like 'thinly-veiled threat" (or in this case, '. . .vendetta')
and 'bordering on slander'.
Meanwhile, let it be said that those who duck like a quack. . .
Ray
Specs31
>So (if lenses are placed correctly in frame) if you look away from anything
>straight ahead say a half
>inch from center of lenses you will have no prism effect with the RT lens but
>(1/2" = about 13mm)
>4 x 1.3CM= 5.2 diopters of prism imbalance. You will see double (if the left
>eye can see)
>Besides there are all kinds of other devils at work such as the magnification
>that travels with a
>+4.00 lens and things should also appear curved in a wierd way etc etc.
>
>
sounds like a job for "slab man"...can see around 90 degree corners with out
blinking an eye....can trip over steps with the ease..... can can look down and
flip you the bird twice with just one hand...or so it appears to
him..:-)........
but there is an old trick that some people tend to forget.... run that
O.C. clear down into the bifocals and push the imbalance of power off the field
of sight....
good post vernon but i think it's a losing battle arguing with Ray... he
wants every term word and spelling to be exact and to fall into parameters he
has deemed perfect....
by the way ask a lab to convert prescribed prism that is supplied in
degree's and watch them spin out of control..:-)
and if you really wanted to drop to the microscopic level that ray is
working on ...every job i make or atleast 99% of them and every job you
dispense has unwanted induced prism....
IF you did not take and supply the OC for each eye on every job..... say i
have a pair of flat top 28's 99% of the time i won't get a OC requested in the
lab so i usually just fit it 6 mm above... but say you had an rx of +3 od +1 os
...and the eye hit it at 10 mm above the seg line..but since i wasn't given any
reference points i grind it at 6 above....than where the person is looking
through the lens they are picking up the imbalance caused by the different
powers prescribed... so if you want to nit pick than we do it wrong in general
more often than we do it exactly right.... but since the eye is accomidating
and usually the induced prism is not that much than it passes... but if we were
on "ray"s scale of exact numbers and definitions we would be in a world of
hurt...
boy will this drive him crazy.... now besides bashing OD's he can start in
on us lowly little lab rats that are optically handicapped when it comes to
knowing optics... or atleast according to Ray and his "OD" buddy who thinks i'm
an optical ninny....
>Vernon, optometrist for over 45 yrs
>Ohio State '52
Must be a pretty popular place...three of the OD's work for went to O.S.U......
as for proof reading??...you think i would do that??...i'm one of the worst
people in this group when it comes to just hacking away and spelling and
leaving out letters or transposing letters....some days i just feel
dyslexic...and some days i feel like i'm not...but as long as you get the
general idea across than no harm done i guess......
hope ya had a good turkey day......
Quote of the day :"Time is the best teacher; Unfortunately it kills all its
students!"
jeff (gained 10lbs.) trail....put on another 10 before christmas if this keeps
up......
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
.............
>Prisms are seldom over 5D.
That doesn't look like a delta to me. It's a dee, and it's confusing
the hell out of me. Everyone uses 'D' for convergent/divergent
diopters. Exactly *what* do you think 'prism diopter' or ' ^ ' does
for you that ordinary 'degree' doesn't? 'Degree' makes it clear that
you're dealing with a dimensionless quantity that only compares
(ratios) two linear dimensions, a diameter and a circumference. A
prism bends light or an image through a certain angle; even ODs
realize that. So why use a stupid unit name that confuses with a
totally different entity that measures the convergence or divergence
of rays of a beam of light or magnifies or minifies an image and
relates reciprocally to a certain distance or reciprocally to the sum
of reciprocals of certain distances, rather than to the dimensionless
angle through which the beam or image is deflected? It's OK to do as
a surveyor does, and use percentage of grade, rather than angle, if
you have to, but it certainly doesn't gain you any thing in optometry,
because, for other purposes to do with the eye, such as visual fields,
you lay everything out in terms of angles from the optical axis. A
surveyor wouldn't turn around and measure angles or percentages of
grade in paces per mile, for instance.
>Both OMDs and ODs and Opticians use prism diopters. Degrees are used in
>calculations for
>strabismus surgery. And also with some measuring and/or orthoptic (training)
>instruments that pivot
>around the eye. Generally dealing with large amounts there.
So why not be consistent, independent of the magnitudes used, Visual
fields use both small and moderate angles. Would you advise their
using prism diopters for small angles and degrees for large ones? I
don't understand your angle, I guess.
>Also the famous Prentice's Rule. Prism power = Lens Power X Distance from
>optical center of the lens in cm.
So what about it? Make it: prism degrees = 1/2 x lens power x
distance from optical center in cm (or use several decimals of
accuracy toward the true multiplier, in place of '1/2'). An OD can't
remember one multiplier in an approximate equation?
> And back in the days of glass (and before computerization) grinding 1 mm more
>thickness on one
>side of a 50mm blank than the opposite side equaled one prism diopter.
>
>Remember the prism diopter concept works because we measure, manufacture, and
>inspect using the same concept. Can't very easily measure in degrees.
Now, what on earth does that mean? Everybody can measure anything as
easily in degrees as in anything else. And using something else
certainly doesn't imply using terminology that is the same as
something totally different. The rest of the world can take an
arctangent, why can't optometrists? And the very bottom line of all
of this is that, people who don't Mickey Mouse around with people,
like industrial OPTICAL PHYSICISTS and ENGINEERS, use prisms all the
time, and NEVER USE PRISM DIOPTERS; the use ***DEGREES***. Look in
any industrial optics catalog, for cryin' out loud. Most often what
you want to know is how many degrees you need to bend a beam of light.
So you look up a prism that says it will bend a beam that number of
degrees. Go ahead, look in any optics catalog that doesn't cater
especially to optoms. Any physiciist, engineer or tech who mounts
any of this stuff hopefully remembers his high-school trigonometry.
Are you saying optoms have all forgotten it?
>And we
>are working with thin lenses and small amounts of prism. IT WORKS!!
So do Roman numerals. When in a funhouse, do as the Romans. When you
don't want to get lost in mirrors and lenses and can't play funny
little esoteric games with people, because you interface and compete
with the efficient world at large, YOU DON'T USE ROMAN NUMERALS.
>Now when I wrote a computer lens surfacing program for my lab (back before any
>programs were available commercially) I had to hunt up my old geometry and trig
>books. There I had to deal with degrees and radians etc. The real nightmare was
>keeping the algebraic signs straight for Rt & LT lenses and the calculations
>for sphero-cylindrical lenses. The frame shape and size (in many meridians)
>measurements have to also be known. But I have wandered as usual.
Well, I can't sort all of that out, but I guess, basically you're
saying that you had to remember your high-school trig and had trouble
with it. NOBODY outside of quaint ophthalmic types mess around with
prism diopters that *I* ever heard about. Small angles has nothing to
do with it. Einstein and his buddies were looking for a pretty small
angle of the bending of light in a gravitational field. Do you think
they ever thought about using prism diopters? Oh, now I suppose
you're saying you can't use PDs without prisms. Yeah, and they can't
pay for anything in Britain in pounds sterling, unless they weight the
money, right? Maybe a jeweler would say anything that's small and
valuable would have to be measure in terms of drams or karats or
whatever.
>Below is apart of a table from my friend Troy Fannin's book Clinical Optics.
>
>First 1 degree=0.00175 radian=1.75 centrads
>
>
>Degrees Centrads Prism Diopters %Error (in assuming
>Prism Diopters=centrads)
> 10 17.45 17.63 -0.1
> 15 26.18 26.79 -0.8
> 20 34.90 36.40 -1.4
> etc etc etc
> 57.3 100.00 155.76 -55.8
>_____________________________________________________
Hey, 'centrads'! I like that. I'll only condemn you halfway to hell
if you use that term. At least it doesn't confues with focal
diopters.
>Remember we seldom prescribe over a couple prism diopters.
Well, I'm trying to get something to catch a glimpse of any movement
in the blind inferior temporal region of my left eye and shove it into
the sighted superior temporal region of the same eye. I figure that
will take at least 30 deg of bending for things some 10 ft or so away.
I'm told I can use two pieces of stick-on Fresnel prisms and that I
can get such prisms of up to 30^. Two of such will give me 60^ or
about 30 deg. That's a bit more than a'a couple'.
>Most prism calculations made in the labs is amount of prism needed to be ground
>into a lens to move
>the optical center of the lens so it will end up in the frame in the proper
>place with relation to the eye.
I'm not sure I follow what you're saying here, but it seems to be that
you're talking about some fudging of centers by adding prism, because
of some frame anomaly. Whatever it is, it certainly isn't germane to
the argument. You can't simply add *prism* diopters to *focal*
diopters.
>MORE
>
>If a 5.00 Diopter lens (plus or minus) is placed in front of the eye with its
>optic center 4 mm from the center of the optic axis of the eye there will be 2
>diopters of PRISM power induced. (Prentice's
>formula --- Refracting power x displacement in CM = prism power thus 5 x 0.4=2
>prism diopters
So you already hit Prentice and I responded.
>So if after cataract surgery one eye only you may have an Rx Rt 0.00 and LT
>+4.00.
>
>So (if lenses are placed correctly in frame) if you look away from anything
>straight ahead say a half
>inch from center of lenses you will have no prism effect with the RT lens but
>(1/2" = about 13mm)
>4 x 1.3CM= 5.2 diopters of prism imbalance. You will see double (if the left
>eye can see)
>Besides there are all kinds of other devils at work such as the magnification
>that travels with a
>+4.00 lens and things should also appear curved in a wierd way etc etc.
So I'm not gonna try to follow all of that. You know as well as I
that THERE IS NO DIFFERENCE BETWEEN PRISM DIOPTERS AND DEGREES EXCEPT
A NUMERICAL FACTOR. That's the bottom line, no matter how much of
this optometric empirics you dump on me. Prism diopters / centrads
(which I had never heard of before) are nothing but a bad habit that
makes things difficult for everybody except someone who gains from
snow jobs.
>Wife says turkey is waiting. Happy Thanksgiving to all.
Ya wanna talk turkey or ya wanna talk prism diopters; that is the
question.
>Vernon, optometrist for over 45 yrs
>Ohio State '52
That's an imperial peck o' pickled prism diopters.
>Sorry I don't have a chance to proof read. I can delete flames but the wife is
>something else. :-))
Yep, I guess you'd starve to death and go down in flames if it weren't
for her.
Ray (LXVI years in the *real* world)
Dr. P. Rozanec
>Some day I'm going to print a study of the types of people who use
>terms like 'thinly-veiled threat" (or in this case, '. . .vendetta')
>and 'bordering on slander'.
>
You seem to have a lot of time on your hands. If you have something
to post on visual/ocular matters, then post it here. If you have
something about whether your prostate is swollen, post it to sci.med.
If you have any psychological studies post them somewhere else.
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>In Yet Another Worthwhile Post, Ray Chamberlin seized the opportunity to say:
>>
>> Some day I'm going to print a study of the types of people who use
>> terms like 'thinly-veiled threat" (or in this case, '. . .vendetta')
>> and 'bordering on slander'.
>
>Be sure to include those who use "Mickey Mouse" and "don't know what
>the hell they're talking about. "
>
>> Meanwhile, let it be said that those who duck like a quack. . .
>
>That's the nice thing about newsgroups, isn't it? You can say anything
>you like; whatever pops into your head. Everyone has the benefit of
>your point of view.
A very thoughtful post, but for inaccurate data again: My name isn't
Chambers.
Ray
Specs31
>Well, I can't sort all of that out, but I guess, basically you're
>saying that you had to remember your high-school trig and had trouble
>with it. NOBODY outside of quaint ophthalmic types mess around with
>prism diopters that *I* ever heard about. Small angles has nothing to
>do with it. Einstein and his buddies were looking for a pretty small
>angle of the bending of light in a gravitational field. Do you think
>they ever thought about using prism diopters? Oh, now I suppose
>you're saying you can't use PDs without prisms. Yeah, and they can't
>pay for anything in Britain in pounds sterling, unless they weight the
>money, right? Maybe a jeweler would say anything that's small and
>valuable would have to be measure in terms of drams or karats or
>whatever.
>
>
I THINK YOU got it at last...and you even said it, not one of us in the
industry....your Quote
" NOBODY outside of quaint ophthalmic types mess around with
prism diopters that *I* ever heard about""""..............
doesn't that prove the point???.....we each understand what we are talking
about, so just becauase you don't than it must be wrong??? .... if it is
understood across the board in the industry than i would say we outnumber you
...or should the whole optical industry rethink and do it by "ray's law".....I
don't think so....
you should be more carful when you go into a tirade ray, you just shot
down any argument you could make by that one little quote.....
it kills you to admit that just because we don't do it "ray's" way than we
as a industry are wrong......
but you are going round and round and saying the same things over and
over...when dealing in prism it can be done or written in degree's or
diopters.....
so no matter if its written in degrees than it still has to be translated
into diopters .....and than when it is ground and checked in with a vertometer
or lensometer ....the field you check it in is broken up quadriants of
diopters.... so whats the difference??
seems to me you are just wasting bandwidth repeating the same thing
vernon said but in your own little way ...the end result wheather it be in
diopters or degree's is that the amount of prism and the direction is still
going to be the same....seems simple enough to me....why can't you grasp
that??... i think you did or you wouldn't have made the quote mentioned
above... now your just going to try to get a rise out of vernon just because
you enjoy arguing...
>I'm not sure I follow what you're saying here, but it seems to be that
>you're talking about some fudging of centers by adding prism, because
>of some frame anomaly. Whatever it is, it certainly isn't germane to
>the argument. You can't simply add *prism* diopters to *focal*
>diopters.
as usual you can do exactly what vernon is saying and you just are not
grasping the optics of what he is talking about... i know you can't understand
prentice rule and how it relates to induced prism..you already proved that...
and you sure can't seem to comprehend how you manipulate optical centers and
GFP to get a funtional lens into a frame....so what exactly is your
argument??if you don't understand it than it must be wrong??
i think you lost sight of this thread and now are just trying to
ramble.....
the question is "can you convert degree's to a prismatic mesurement in
diopters" ......
the answer is yes......end of thread!!!!!!!!!!
as for the rest of your post to vernon....all it is is one of your personal
attacks ...usually fueled by ignorence and your lack of actually trying to
understand that "we" may know what we are talking about ...even though we don't
or are not doing it "RAY'S" way........
why don't you just shutup and listen and read for once and if you have
questions about how we did it than ask...but jumping in and correcting or
trying to correct the whole optical industry because you don't agree is just
silly.....
Jeff
VernonH
In article <347e793...@news.sirius.com>, ra...@sirius.com (Raymond A.
Chamberlin) writes:
>ver...@aol.com (VernonH) wrote:
>
.............
>Prisms are seldom over
>5D.
That doesn't look like a delta to me. It's a dee, and it's
>confusing
the hell out of me. Everyone uses 'D' for
>convergent/divergent
diopters. Exactly *what* do you think 'prism diopter'
>or ' ^ ' does
for you that ordinary 'degree' doesn't? 'Degree' makes it
>clear that
you're dealing with a dimensionless quantity that only
>compares
(ratios) two linear dimensions, a diameter and a circumference.
>A
prism bends light or an image through a certain angle; even ODs
realize
>that. So why use a st
Ray,
I'll take it a bit at a time. You're letting your prejudice agenda cloud your
mind.
And I know you have a brilliant mind. I'm surprised you haven't picked
different windmills to tilt. You are wasting your talent on this field of
"incompetents, stupid,
etcetcetcetcetc" as you see us. Pick on someone your own size in materia gris.
You know that symbols like the delta sign don't travel the net well.- like the
"ń" (Spanish letter enye) you jumped someone about a while back.
There isn't a bit of confusion to the 3 O's as to what a prism diopter is and
how to handle it..
You conveniently left out of your post one of the big reasons for the prism
diopter
concept. Let me yell it. THE TESTING SURFACE IS FLAT, GET THAT IN YOUR HEAD!!!
LIKE eye--------------->wall--| NOT eye------------------> curved
surface----).
"-----" represents the testing distance 20' or 6M.
Vernon
Will be back later
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
...............
>
> by the way ask a lab to convert prescribed prism that is supplied in
>degree's and watch them spin out of control..:-)
Hey, if I get a good VRML movie program set up right, can I do that
online? These verbal spins are getting boring.
> and if you really wanted to drop to the microscopic level that ray is
>working on ...every job i make or atleast 99% of them and every job you
>dispense has unwanted induced prism....
My lord! I think you should be given a prism term for that. (That
one I could just *not* resist. ;-) )
> IF you did not take and supply the OC for each eye on every job..... say i
>have a pair of flat top 28's 99% of the time i won't get a OC requested in the
>lab so i usually just fit it 6 mm above... but say you had an rx of +3 od +1 os
>...and the eye hit it at 10 mm above the seg line..but since i wasn't given any
>reference points i grind it at 6 above....than where the person is looking
>through the lens they are picking up the imbalance caused by the different
>powers prescribed... so if you want to nit pick than we do it wrong in general
>more often than we do it exactly right.... but since the eye is accomidating
But if, in some case, it ain't, the attachment known as the customer
('patient', by those who want their trade to look like medicine) may
not be accommodating, but he/she doesn't know whose butt to kick.
>and usually the induced prism is not that much than it passes... but if we were
>on "ray"s scale of exact numbers and definitions we would be in a world of
>hurt...
Two ODs here seem to be already in that world. There brains don't
seem to be 20/20, but they sure don't wanna go for any correction.
Shouldn't hurt the world too much though.
> boy will this drive him crazy.... now besides bashing OD's he can start in
>on us lowly little lab rats that are optically handicapped when it comes to
>knowing optics... or atleast according to Ray and his "OD" buddy who thinks i'm
>an optical ninny....
Oh, come on, are you tellin' me that's the first OD who ever thought
you were a ninny (whatever that is) ? I think you oughtta take some
of 'em through your lab and give 'em a quiz afterwards -- not in
words, but in "You can have your glasses back after you take this
blank and make a replica of them and read the 20th line on this
slightly Trail-ized Snellen chart to my satisfaction." ;-)
>
.............
>
Ray
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
..............
>
> I THINK YOU got it at last...and you even said it, not one of us in the
>industry....your Quote
No, I don't got it. Can't follow the logic here. Maybe there're
words left out. But the 3 Os should also be part of the *optical
industry* overall. Most of the *optical industry* doesn't deal with
objects mounted on or in the human head. To them an angle is an
angle, not a prismatic deflection that requires a name that confuses
with lens power versus a beveled edge that doesn't. Look in any
industrial optics catalog -- Rolyn, OptoSigma, Ross, Esco, Edmund
Scientific, etc. -- and show me one mention of a prism diopter. These
company's catalogs are full of prisms. Quaint little hold-out stuff
only raises costs to all and makes the perpetrators look like
parochial shamans trying to make something straightforward look like a
big only-we-can-do-it deal to the public.
>" NOBODY outside of quaint ophthalmic types mess around with
>prism diopters that *I* ever heard about""""..............
>
> doesn't that prove the point???.....we each understand what we are talking
>about, so just becauase you don't
*I* know what you're talking about; the problem is that many others
think you have some big, complex deal going, rather than just a stupid
little angle. They either have to lump it or waste time reading up on
you guys' little fun and games.
>than it must be wrong???
I didn't say it was "wrong", it just sorta shows where things are at
3-O-wise.
>.... if it is
>understood across the board in the industry than i would say we outnumber you
>...or should the whole optical industry rethink
See above about "the optical industry"'s thinking.
>and do it by "ray's law"
Yeah, I invented the degree and proclaimed that all angles shall be
measured by it, right? Of course, if you wanna play it really
straight, ya hafta get rid of the temperature 'degree', since it
confuses with the angular 'degree' (not to mention the PhD degree, the
3rd degree and the nth degree). But, hey, reasonable people are doing
just that. The official abbreviation these days, as I understand it,
for points on the Fahrenheit or Celsius temperature scales, is simply
x F or x C, not x ° F or x ° C. Of course, there's the problem with
'minutes' and 'seconds' when they measure angles, because these units
are supposed to measure time; but the next time a couple of important
(?) ODs die, we can replace the 'minute' and 'second' of arc with
their names. ;-) (Oops, I guess you're not back from that coffee
break you took. Well, things may pick up any moment now.)
.....I
>don't think so....
Ray's law is: Do it right the first time. Less call-back that way.
> you should be more carful when you go into a tirade ray, you just shot
>down any argument you could make by that one little quote.....
Well, I didn't promise things were going to pick up right away.
> it kills you to admit that just because we don't do it "ray's" way than we
>as a industry are wrong......
You ain't a industry, Man, you's a cramped corner of a industry what
never got cleaned. Breadcrumbs and roaches everywhere.
> but you are going round and round and saying the same things over and
>over...when dealing in prism it can be done or written in degree's or
>diopters.....
Then why would labs "spin out" if you gave them degrees (angular ones,
not academic ones) ?
> so no matter if its written in degrees than it still has to be translated
>into diopters .....
Because diopters go with diehards?
>and than when it is ground and checked in with a vertometer
>or lensometer ....the field you check it in is broken up quadriants of
>diopters....
*Prism* diopters, right? Well, visual fields are broken up into
quadrants of *degrees*, and ODs are licking their chops over them
these days. So who's right and who's wrong?
>so whats the difference??
It's all a matter of degree, I think. We're just going to have to
have lab folks get at least BSs, if only to improve the spelling in
the BS excuses.
> seems to me you are just wasting bandwidth repeating the same thing
>vernon said but in your own little way ...the end result wheather it be in
>diopters or degree's is that the amount of prism and the direction is still
>going to be the same....
Well, of course, if it's supposed to do the same job. But the idea is
to KISS. Everyone, even 3-O types know what a degree is. If stick-on
Fresnel prisms were measured in degrees and sold by ordinary optical
supply houses, they'd probably cost US 10 cents, rather than US$15.
>seems simple enough to me....why can't you grasp
>that??... i think you did or you wouldn't have made the quote mentioned
>above... now your just going to try to get a rise out of vernon just because
>you enjoy arguing...
Now you're out their wandering. There wasn't any argument over the
way of figuring something, only over the nonsense of deciding that the
result, in the case of the bending of light, had to be in PDs, while
in all other cases, it should be in degrees. But also, I never was
sure whether Vernon was really trying to *justify* the present use of
PDs or just trying to rationalize why that unit historically came to
be.
>>I'm not sure I follow what you're saying here, but it seems to be that
>>you're talking about some fudging of centers by adding prism, because
>>of some frame anomaly. Whatever it is, it certainly isn't germane to
>>the argument. You can't simply add *prism* diopters to *focal*
>>diopters.
>
> as usual you can do exactly what vernon is saying and you just are not
>grasping the optics of what he is talking about... i know you can't understand
>prentice rule and how it relates to induced prism..you already proved that...
Prentiss' law doesn't add prism diopters to focal diopters. Prentiss'
"law" is just a rule of thumb. Some OD here has already stated that.
I didn't deny one could do anything Vernon talked about; I just denied
there was any valid reason for hopping off into PDs, except that
people in the cloisters of ophthalmidom seem to still write in
cueiform and maybe that those units may be easier to chip out of
stone. ;-)))))
>and you sure can't seem to comprehend how you manipulate optical centers
Why do you say that? I get the picture. I certainly don't think you
have to convert angular measure into PDs just so you can use Prentiss'
law though. As I pointed out, a fudge factor 0.5 is just as good as a
fudge factor of 1.0.
>and
>GFP to get a funtional lens into a frame
Hey, you already know I didn't even know where to find the screws that
permit opening the frame in order to get the lens in it. So you might
as well know that I don't even know what a GFP is. Maybe it means
'god-forbidden pest', huh? You ain't gonna frame me. And,
furthermore, would you really want to get me so sharp I'd run off to
FL, amongst all those alligators, and take your job away from you?
>....so what exactly is your
>argument??if you don't understand it than it must be wrong??
If the guild doesn't understand that I understand it, then it/they
must be wrong.
> i think you lost sight of this thread and now are just trying to
>ramble.....
I think somebody never had his optical center in the right place to
begin with.
> the question is "can you convert degree's to a prismatic mesurement in
>diopters" ......
Is that *your* question. Nobody here has asked that question to date;
nobody other than you would.
> the answer is yes......end of thread!!!!!!!!!!
You're making up your own threads now, both head and tail? Do a
retake on the initial post: It asks *how* to convert from one unit to
the other; it doesn't ask *whether* it can be done. Tyner correctly
told him how, but included a comment about the method's only holding
near zero. I then commented on that and went around with Tyner on
that. Then Vernon, admitting that it would likely be a bad move, dove
into the fray. Well, you know (unlike the original poster, who was
soon outta here with his answer) how these neighborhood free-for-alls
go: The next thing you know Ha-Ha Man is in there tryin' ta tear up a
little flesh, 'cause things get awful boring in the lab after ya know
it all. And thus we get the whole 9 yards o' cloth, instead o' just a
thread. But bandwidth is cheap these days. . .and as the man says, it
keeps 'im from annoyin' 'is wife.
> as for the rest of your post to vernon....all it is is one of your personal
>attacks ...usually fueled by ignorence and your lack of actually trying to
>understand that "we" may know what we are talking about ..
Hey, what's this "may" stuff. You don't really wanna let the public
hear you say *that*, do you?
>.even though we don't
>or are not doing it "RAY'S" way........
Yup, the rest of the technical world's way is "Ray's way".
> why don't you just shutup and listen and read for once and if you have
>questions about how we did it than ask...
Say, have you *read* the references I sent you after you asked for
them? Any questions
>but jumping in and correcting or
>trying to correct the whole optical industry because you don't agree is just
>silly.....
You gotta get educated on what the "whole optical industry" really is,
Man. It ain't putting specs on flamingoes.
Ray (The full term is 'life in prism'.)
VernonH
>
>Both OMDs and ODs and Opticians use prism diopters. Degrees are used
>in
>calculations for
>strabismus surgery. And also with some measuring and/or
>orthoptic (training)
>instruments that pivot
>around the eye. Generally
>dealing with large amounts there.
So why not be consistent, independent of
>the magnitudes used, Visual fields use both small and moderate angles.
>Would you advise their using prism diopters for small angles and degrees for
>large ones? I don't understand your angle, I guess.
Ray,
OMDs and ODs use degrees with visual fields. Fields instruments
have a CURVED BOWL. We are not going to write a lens script using
visual field info. These are completely different endeavors. I think in your
case you
have or are considering trying to take advantage of a patch of the small
remaining visual field in the "bad" eye. This would be one of the few times in
my
45+ yrs as optomer that degrees would have to be translated into Prism Diopter
so
the lab could process the lens. I doubt if it would work. It would take a lot
of retraining of your visual brain. Be interesting though. I fear you would be
dealing with a lens 1" to 2" thicker on one edge than on the opposite! I don't
where you would find a lens blank that thick. Seems you had an idea of power
needed. (I translated thickness to inches for other listees but we use metric
system
Don't have to do that with my Mexican clientela and certainly not for Ray)
Years ago, and we still sometimes use a very large black cloth for taking
fields. It has the degrees from the macula stitched in many concentric circles
plus some other landmarks (blind spot).
(ASIDE: In my office over half of the 8 to 13 yr olds are malingerers.and also
almost everyone who is trying to get compensation for some accident etc. There
is a fairly simple test to prove malingering using this old non-computerized
fields test.)
>So why not be consistent, independent of
>the magnitudes used, Visual fields use both small and moderate angles.
>Would you advise their using prism diopters for small angles and degrees for
>large ones? I don't understand your angle, I guess.
We are not going to be prescribing prism for those large angle squint cases.
(Squint = strabismus and is 4 letters shorter)
The surgeon will only be thinking in terms of degrees for corrective surgery.
That is
a whole different ball game.
We generally cannot measure angle of strabismus with our "refracting etc"
equipment. The location of a light reflected by the cornea gives us a good
idea of
the squint angle. Makes little difference to us if it is 25 or 30 degrees. We
will handle
the case the same be it one or the other. If we send patient to a surgeon he
will have to use his skills in deciding how much to change the leverage of one
or
more of the six strong extraoccular muscles and/or some check ligaments.
I had a patient, Ray hates for us to use that word, Sat. One of her complaints:
seeing double times. Found she needed 2 BDOD. So to her lens prescription we
add prism 1 BDOD and 1 BUOS. We split the prismatic effect between the two
lenses for cosmetic reasons as well as the better optical quality with smaller
prisms.
Nuf for now.
Vernon Hammond, Optometrist
Ohio State '52
VernonH
>>Also the famous Prentice's Rule. Prism power = Lens Power X Distance
>from
>optical center of the lens in cm.
So what about it? Make it: prism
>degrees = 1/2 x lens power x
distance from optical center in cm (or use >several decimals of
accuracy toward the true multiplier, in place of '1/2').>An OD can't
remember one multiplier in an approximate equation?
Ray,
Why go to all that trouble. REMEMBER THE AMOUNT OF PRISM NEEDED WAS DETERMINED
USING A FLAT WALL.
Now why did you leave this part of my post out of your
retort????????????????????????????????????????????????????????????????????
??????????????????????????????????????????
VernonH
>Now, what on earth does that mean? Everybody can measure anything as
easily
>in degrees as in anything else. And using something else
certainly doesn't
>imply using terminology that is the same as
something totally different. The
>rest of the world can take an
arctangent, why can't optometrists? And the
>very bottom line of all
of this is that, people who don't Mickey Mouse around
>with people,
like industrial OPTICAL PHYSICISTS and ENGINEERS, use prisms all
>the
time, and NEVER USE PRISM DIOPTERS; the use ***DEGREES***. Look
******************************8888888
Ray,
So what! WE USE A FLAT WALL TO DETERMINE PRISM POWER NOT A CURVED WALL. and
our prisms are very small, seldom over 5 prism diopters and
generally under 2. Why do you ignore the FLAT testing wall??
Of course I know that physicists use degrees. We take optics for a year (at
least
we did 50 years ago at Ohio State) over in the physics department. At the
blackboard every day tracing rays all over the place. And now I have to put up
with another Ray que esta' chingui y chingui.
Vernon
VernonH
>Well, I can't sort all of that out, but I guess, basically you're
saying that
>you had to remember your high-school trig and had trouble
with it. NOBODY
>outside of quaint ophthalmic types mess around with
prism diopters that *I*
>ever heard about. Small angles has nothing to
do with it. Einstein and his
>buddies were looking for a pretty small
angle of the bending of light in a
>gravitational field. Do you think
they ever thought about using prism
>diopters? Oh, now I suppose
you're saying you can't use PDs without prisms.
>
Ray,
No trouble with the trig & geom but writing the computer program so that
the signs would come out correct is a little complicated. Remember almost all
scripts have a cylindrical component. The formulae get a little wild. The lens
has to end up meeting many thickness requirements all around the edges and the
center.
The optical center has to end up in the correct place. Look at the crazy shapes
frames have and being an engineer you should be able to imagine the amount of
data input necessary to get an acceptable finished product.
The lens grinder has to grind in prism on almost all jobs to get the optical
center where it belongs. He sometimes might get by with using an extra large
size
finished lens but a plus lenses would be thicker than necessary and thus more
unsightly and with more aberrations etc that come with thickness. By grinding
prism he can move the optical center over several mm and calculate critical
thickness to make a better looking job that passes the feds minimum thickness
requirements for safety - but no thicker than necessary for good optics and
best
appearance.
For the script in my other post of prism 1 BDOD and 1BUOS. Let's say the script
is
a plus 5 - to make it simple. (I'm not taking into consideration the frame nor
patients eye separation (PD) )
To get the prism needed just decenter RT lens down 2mm and LT up 2mm.
And you want us to change to a curved exam wall!
Vernon
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
............
>
>I'll take it a bit at a time. You're letting your prejudice agenda cloud your
>mind.
My prejudice! I am the reason everyone, including the 3 Os, for
purposes other than light images, prefers degrees over prism diopters,
and why everyone, including all of the non-3-O optical industry,
prefers degrees in the case of light images, right? Hardly. I just
want to point out, against all the nonsense arguments here, the sort
of thinking that goes on in this holed up little world, the optom
branch of which has been bugging all the state legislatures, and no
doubt oversees governments, to be able to take the public on more
happy, expensive joy rides. See my response to Jeff Trail.
>And I know you have a brilliant mind. I'm surprised you haven't picked
>different windmills to tilt.
Which ones would you suggest. . .and now you asked for it. . .at how
many prism diopters would you like me to tilt them? My interest is
not in just tilting windmills or challenging intellect. Intellect
doesn't run the country or the world, and certainly not the human-body
repair business or those who would like to model their service-for-fee
methods on same. Some of the last double category is here, but this
is not sci.med.optometry; it is sci.med.*vision*. The fee-for-service
people here like to think of this as a home-shopping channel. I think
vision is everbody's business and that it, as with all of the body and
its functions, including parts necessarily dealt with
psychophysically, are parts of the domain in which general science and
common sense hold sway -- however much the fee collectors have twisted
things so that even *they* can't see them in terms of efficient,
pragmatic, functional models which facilitate low-cost treatment.
This NG should not be limited to simply seekers of cures and
practitioners who get off on giving the public answers termed in the
stuff of their cultures.
>You are wasting your talent on this field of
>"incompetents, stupid,
>etcetcetcetcetc" as you see us. Pick on someone your own size in materia gris.
>
>You know that symbols like the delta sign don't travel the net well.- like the
>"ñ" (Spanish letter enye) you jumped someone about a while back.
(Capital) delta isn't even an 8-bit ASCII character on a standard US
keyboard, so that's not a factor. I'm not asking you to send encoding
for a full-Greek font set that almost no one in this group would have.
Other ODs here use ' ^ ' or 'PD' -- anything but another 'D' --
particularly when we're talking about the very problem of confusing
prism with focal diopters. I wasn't *jumping* that person, just
commenting. However, maybe that person intentionally used 'n~ '
because the Net had, at least in the past, not always handled 'ñ'
right. Some people just use ' ~ ' alone.
BTW, I got your 'ñ' ( 'n~') with no problem. Didn't you get mine OK?
I understood most of the Net had gotten that problem cleaned up.
There probably are gateways, though, where it doesn't get printed
right.
>There isn't a bit of confusion to the 3 O's as to what a prism diopter is and
>how to handle it..
Well, I didn't really claim there was. But actually, since *you*
bring that up, I really believe there is some, and I think some of
Tyner's thinking on limitations to be put on it was a little hazy.
>You conveniently left out of your post one of the big reasons for the prism
>diopter
>concept. Let me yell it. THE TESTING SURFACE IS FLAT, GET THAT IN YOUR HEAD!!!
> LIKE eye--------------->wall--| NOT eye------------------> curved
>surface----).
>"-----" represents the testing distance 20' or 6M.
Well, I won't shout, because it's very clear that wouldn't make you
understand (and I won't translate it into Spanish, because I'm not
that great at Spanish (and because Spanish isn't your first language
anyhow, is it?), but however flat an image surface is, it doesn't
justify discarding units of degrees, minutes or seconds and
substituting for them another esoteric unit, 'prism diopter' --
especially one which confuses with another unit, even of a different
fundamental dimension, which is even more prevalent in your discipline
-- namely 'diopter'. OK, you don't understand; you never will; you're
a nice guy; this problem certainly doesn't disqualify you, from
anyone's perspective, as an optometrist or optician; but flatness of
an opposite side of a right triangle does not disqualify or degrade
the use of standard angular measure for the opposing/subtending angle,
and angular measure is robust, even where someone has kicked a hole in
your image screen. An angle is an angle, and it makes no sense to
think an angle of light-image deflection should require a different
unit than does one that, say, specifies the chamfer of the edge of a
lens -- on *any* *logical* basis.
Ray
VernonH
>Well, I'm trying to get something to catch a glimpse of any movement
in the
>blind inferior temporal region of my left eye and shove it into
the sighted
>superior temporal region of the same eye. I figure that
will take at least
>30 deg of bending for things some 10 ft or so away.
I'm told I can use two
>pieces of stick-on Fresnel prisms and that I
can get such prisms of up to
>30^. Two of such will give me 60^ or
about 30 deg. That's a bit more than
>a'a couple'.
Ray,
Sorry I didn't find this data when responding to your flame.
Fresnel lenses are not ground and the 30 deg was determined by fields test ,no?
Fresnel was a French engineer and physicist. He come up with this concept in
early 1800's. The lenses were used for lighthouse beacons.
The Optical Sciences Group of San Rafael, California about 30 yrs ago developed
an adaptation of
the Fresnel lens. The come in many powers up to 30 PRISM DIOPTERS. You better
go and raise hell with that bunch!!!!!!
They don't last very long since they are a thin plastic membrane.
By the way how do they pronounce Fresnel out thataway. At OSU we weren't
allowed to pronounce
the "s" but in Texas I always hear it pronounced as if it were an English name.
Vernon
Ajúa (Ah HOO ah) is a Mexican low key yell of satisfaction. Forgot to answer
that.
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
.............
>
> using the word "diopter" after a rx power or a prescribed amount of prism
>is not two entirely different things...
>
> when dealing in focal power and corrective power (prism) than it is
>measured in terms of diopters...and degree's ... say you had a +1 OU with
>prescribed prism 2 BO/ou ....than when i would be talking about that lens it
>would be phrased as" 1 D WITH 2D base out".... when dealing in prismatic lens
>you can get it one of two ways....with the prescribed prism in diopters or
>OD/OMD will give you the power in diopters and give you the prism in degrees
>and you have to convert that degree's of prim into a number that is
>transferable.....when checking any RX the lensometer is based on three
>things...power,axis and prismatic diopters....
You mean 'spherical and cylindrical dioptric power' = 'reciprocal of
same focal lengths', the 'orientation of the axis of such cylinder'
and 'amount of off-optical-axis deflection'. These are not magical or
required names; they are just choices that are independent of *units*.
'Prismatic diopter' is not a designation that has been kept
independent of any unit it might be measured by.
> when you look into a lensometer will see those three things...one solid
>line for cylinder (astigmatic correction) three smaller lines at a 90 degree
>angle for spherical correction...and than rings that are set for measuring
>distence in prism diopters....
> where the two lines cross (spherical,cylindrical) is the optical
>center...and where they fall at on those rings is the amount of prismatic
>effect you want or need.......or if done incorrectly you don't want or need....
I've never looked into a lensometer, BUT: Though it might not be as
easy as sticking a tape with a different scale over a scale in the
lensometer, the use, in that instrument, of rings spaced at certain
values in prism diopters is completely as arbitrary as using inches
and feet on a linear scale in this country (US), rather than meters.
Rings can just as well be placed at integral values of minutes of arc
and degrees. You tend to think of "prism diopter" as a *dimension*;
it is not; it is a *unit* arbitrarily chosen for a dimensionless
measure that is functional and not arbitrarily chosen, i.e., image
deflection off the optical axis, simply an angle. All angles,
including this virtual type, have *no* physical dimensions (length,
time, charge, etc.); they can be specified by any of the trigonometric
ratios of lengths of a right triangle which includes the subject
angle. One of these trigonometric ratios is the arctangent. The unit
'prism diopter' was arbitrarily (well, within some *well-intentioned*
criteria) chosen as defined by words which reduce to an arctangent
function, as OD Mike Tyner stated correctly in his first post of this
thread.
> same as using prentice law for finding the amount of induced prism if
>the pupilary distence is not correct. i can calculate it all out or just check
>it in a lensometer
I don't follow as to what is the same as what else, but Prentice's
"Law" is simply a rule of thumb that multiplies two quantities -- one
of which, the off-axis deflection, is measured by "The Guild" in prism
diopters. When measured in degrees, one simply has to divide the
answer by 2. Big deal. Your calculating facility is not harmed in
the slightest.
> someone comes in with a pair of lens ..they wear a pd of 63 but when i
>check the lens i would put them in the lensometer and move the lens till the
>two sets of lines cross dead center of the rings...than dot it up...next just
>measure that distence between those two dots and compare it to the pd needed
>and than you know if it is a induced prism problem....than measure out the
>needed pd and put it back in the lensometer and than see where the two sets
>cross.....if it is outside of that center than you know it is incorrect ....you
>have dead center and than a half diopter ring and 1 diopter on out (2,3
>.....etc etc)
> its very easy to plot out ...
All of this works out every bit as easily in degrees, with a
lensometer marked in degrees (and maybe half degrees). This switch is
no different from switching between feet and meters.
> in the industry most of the time when you talk about power they just say
>if it is + or - ...and prism is just referred to as base out/up or base in/out
>... even though the word diopter is used after those two things you just don't
>use the word that much....
Well, that is preferable to using the Di word, but it doesn't justify
*not* using the De word and simply a multiplier of 0.5 or a
recalibrated lensometer, so that you'll be consistent with the *real*
optical industry and the whole rest of the world.
> same as any industry you have key words that have a wide variety of uses
>and attachments but you tend to drop that word when talking to someone in the
>same industry because its a given that you each know it already... as in the
>example i used (+1sph. OU/2BO) when a optician or OD or OMD is talking to me
>s/he isn't going to say +1 diopter with 2 diopters base out... why would they??
>thats a given to a fellow optical person??
So, very well, in the outside world, when words get dropped for a
reasonable cause, pretty soon they don't exist anymore. So get your
pedagogy to drop entirely the word 'diopter' in respect to prisms.
But I think it's better to switch over to degrees like the rest of the
world, including most of the optical industry, *before* you drop the
Di word, because then everybody knows your correct number is how half
what it was, and you don't have to guess which unit it's in.
> you can nick pick , slash and burn any industry if you try to use every
>term and word when ever you think it should be used as a layman looking in from
>the outside....
That's a duck like comes from a quack. You're certainly not a quack.
But your subindustry looks funnier the more it uses such idiosyncratic
distortions of common scenarios.
>i can give plenty of examples in the optical industry where
>words are used that we all know the meaning but translated to a layman the seem
>contradictive... take power... when talking about power in lens in the industry
>you would say its in quaters or twelths... even though you know its not
>exact...
Do you people really all speak of twelfths instead of eighths when you
refer to halves of quarters? When you first got into an argument with
someone quite a while ago on that score, I thought that was merely a
momentary aberration of yours resultant of confusion by the notation
for it, '0.12' -- an approximation of 0.125, which, of course, is 1/8.
Do optoms and ophthalms also use that terminology? Somehow, I don't
think so. So, by your thinking, if they don't, they're in another
"industry", is that it?
>but you know that when dealing with a power below a quater is not
>really effecting much of anything...on paper if you work out the mathmatics it
>may look like a large number but translated into how it effects visual acuity??
>its nothing...
Hey, well, OK, little mistakes are not biggies. We won't fire you
. . .yet. Now, back to what those flies had for breakfast.
> its the same in industry and i'm sure you could probably rattle off a
>few yourself that you used that to an outsider may have looked contradictory or
>even way off base but to another person that does the same thing you do it
>looked ordinary.....
Oh, EEs use silly names. Take 'floppy'. It mostly hasn't been floppy
for a decade. And I'm not sure whether they get on the bandwagon
lately on which people are heard to speak of writable and rewritable
CD-ROMs or not; but ROM, of course you know, stands for read-only
memory. (Yes, I know: You think I'm a write-only memory.)
Ray (An angle by any other name does not subtend as sweetly.)
Raymond A. Chamberlin
eye...@nospam.net (Dr. P. Rozanec) wrote:
>
...............
>
>You seem to have a lot of time on your hands. If you have something
>to post on visual/ocular matters, then post it here. If you have
>something about whether your prostate is swollen, post it to sci.med.
>If you have any psychological studies post them somewhere else.
I posted on a visual/ocular matter as "Who's the Weirdest of Them
All", but you didn't seem to like it. At least that's what I deduced
by this sweet little message:
:>Just another useless post above from someone willing to waste
:>bandwidth.
:>
:>An old fellow with a lot of time on his hands. So full of it the eyes
:>are brown.
:>
:>I'll take back the last line; no need to get personal.
Didn't I interpret this right? I guess if you're an OD, though,
privilege allows you to extend the permissable range of bodily matter
that is discussable here -- just a bit.
Ray (Can't please 'em all, so don't please any of 'em.)
Specs31
Ray maccaroni wrote:
> Most of the *optical industry* doesn't deal with
>objects mounted on or in the human head. To them an angle is an
>angle, not a prismatic deflection that requires a name that confuses
>with lens power versus a beveled edge that doesn't. Look in any
>industrial optics catalog -- Rolyn, OptoSigma, Ross, Esco, Edmund
>Scientific, etc. -- and show me one mention of a prism diopter. These <yada
yada yada>
BUT we are not talking about that facet of the optical industry ... only
you could tie those things into a post having to do with vision and the three
O's as you like to say....
thats almost as bad as lumping every engineer into a "same heading
group"... you know as well as i do that a civil engineer and a electrical
engineer are not going to be using the same terminoligy... your really reaching
in this thread now.....
>You ain't a industry, Man, you's a cramped corner of a industry what
>never got cleaned. Breadcrumbs and roaches everywhere.
but this "cramped corner" is all in agreement on what prism is...and how it
relates to our Bread crumb infested corner....
>Then why would labs "spin out" if you gave them degrees (angular ones,
>not academic ones) ?
never said "labs" per say... just certian people in the labs... not every
lab understands optics... alot of them are the "take the order in and run it
through the computer and than just do what the ticket says"..... but do they
understand what they are doing??? ...sometimes yes...most of the time no...
thats just the downside of being trained in a big lab compared to a small hands
on lab ....
i wish it were different myself and i see the wholesale business
producing "optical" handicapped people every day....as things get more animated
we get less and less of the people that understand what they are really doing
on the "optics" level......
if it was up to me i would make everyone in the optical cross train...
that includes OD's right down... i took classes on refraction just so i could
get a better understanding of thier side of the coin... and i make everyone
that works for me cross train in production and sales... i think it makes for a
more well rounded and educated dispenser/tech and the people who benifit most
from this is the patient.... thats my concerns... could give a crap if you or
anyone else agree's with me or not
>The next thing you know Ha-Ha Man is in there tryin' ta tear up a
>little flesh, 'cause things get awful boring in the lab after ya know
>it all. And thus we get the whole 9 yards o' cloth, instead o' just a
>thread.
if you notice when i deal with someone other than a layman thier is no "ha
ha"... when it comes to optics on this scale of conversation its time to put
the ha ha's away ....
and when i make a post i try to cover it ..not like some people who pick
apart a post and drop "one liners" in it and expect to be taken on a serious
note....
>retake on the initial post: It asks *how* to convert from one unit to
>the other; it doesn't ask *whether* it can be done. Tyner correctly
>told him how, but included a comment about the method's only holding
>near zero. I then commented on that and went around with Tyner on
>that. Then Vernon, admitting that it would likely be a bad move, dove
>into the fray. Well, you know (unlike the original poster, who was
>soon outta here with his answer) how these neighborhood free-for-alls
>go:
and the answer's that both of those Doc's posted were correct each covering
slightly different aspects of the same problem.....
>The next thing you know Ha-Ha Man is in there tryin' ta tear up a
>little flesh, 'cause things get awful boring in the lab after ya know
>it all.
first.. i never claimed to know it all..have i ever said i did??..nope...
next, the post i made were giving the COS squared of the angle times the prism
= horz. prism (180)
the SIN squared of the angle times the prism = vert. prism (090
is away to convert it....don't see any flesh being torn there?? maybe someones
little ego got bumped.. but no flesh flying.
when i try to post i like to explain it... not just one line it to
death...... so if you say the whole "nine yards"... so be it.....you are not
the only one reading this thread... so if you don't care if i'm right or wrong
maybe someone else reading this thread will learn something...and thats why i
come here to begin with... even if it kills you to atleast think about it...
some of us actually care about what we do and are trying to improve the optical
trade..... so if you think i'm an idiot thats fine by me.. i could care less..
but if someone learns something in any of these "9 yard posts" as you prefer to
call them than i have done something i set out to do
>Say, have you *read* the references I sent you after you asked for
>them? Any questions
not yet... ordered the back issue that you said it was in....takes two to three
weeks to get here... unless you know where i can find it out on the web
somewhere....and as for questions??... thats the difference between me and
you... i wouldn't think twice about asking anybody anything... thats how you
learn..... sometimes it's easier to learn with your mouth shut and listen.. try
it sometime...and maybe be or show alittle respect once in awhile.. when
attacked people usually attack back....
>You gotta get educated on what the "whole optical industry" really is,
>Man. It ain't putting specs on flamingoes.
in the way i deal with the "optics industry" it is... i'm not interested in
optical engineering or optics as in lasers or any other field of optics thats
out there.... i have enough trouble dealing with the optics that "puts specs on
your face"... let alone trying to deal with it all on a grand scale ..as some
people i know on here try to do... :-)
have fun picking this apart... i left plenty of openings for your one
liners.....
TaTa
jeff
Specs31
ray bitched:
>Well, that is preferable to using the Di word, but it doesn't justify
>*not* using the De word and simply a multiplier of 0.5 or a
>recalibrated lensometer, so that you'll be consistent with the *real*
>optical industry and the whole rest of the world.
if you don't consider this optics than why don't you just leave this group
alone......
i'm tired of your bitching and moaning and how you like to change the
threads around... now since you can't comprehend the use of the word diopters
in what we were talking about... all at once now we all need to change to meet
the rest of the so called "real" optical industry ....
whatever... i'm tired of dealing with you... you are rude, and you can
spout all your usual bullshit about how it is your "right to correct all of us
optical idiots" and you can continue your oneline insults and all the rest....
i'm sick of it.
lets put this in a non optical term you can deal with piss off.....
from now on find someone else to argue with.. you always take it on a
personal attack and never do i see you discussing what the thread is about....
you always wait till people answer than you just pick it all apart with stupid
little one liners and unrelated things that were in the post that you usually
lift out of context.....
i've had enough....
jeff
Mike Tyner, OD
VernonH wrote:
>
> Are you aware how we change the prism power to take the various measurements
> (during patient testing)??? Remember most phoropters can produce at least 30
> prism diopters. And we can use a nice linear scale.
Ray won't be happy until we change the scale on all existing phoropters and
lensometers and other instruments.
I'll change mine if he'll cover the cost.
Specs31
vernon "the bulldog"Hammond wrote: -)
>Vernon Hammond, Optometrist
>Ohio State '52
>
>
You sure you didn't go to Georgia...you been holding back on us...a regular
bulldog fighting in the trenches....
By the way some of us agree with your statements... Ray is not the only
contributer... maybe the most obscurant and the rudest but not the only one
with an opinion....unless of course you are talking to him, than its his way or
no way....
He likes to say "its his right to correct us" but usually attacking someone on
a personal level and insulting them is "not" a correction..
We all in are guilty of leaving out, every facet of an answer and in most
cases, i see fellow "optical" people only expanding the previous post.... and
by stringing a thread, by its end every combination is usually covered... along
with Ray's attempts at humor and trying to show everyone how optically inept we
are by pulling strings of text out of a post and trying to intertwine some
verbal jousting of his own into the middle of it... which by the way has
nothing to do with the answer to the originating post......
am i the only person who has never seen Ray answer a question on optics in
this group?? he waits till we all do and than just interjects his brand of post
into the thread, which is usually combative and insulting, but has no bearing
on the thread as a whole.
He may consider my type of answering a post idiotic, which is fine with
me. but atleast I try to be helpful and not just condescending ... but thats
his style
i have my own... as do all the rest of you that post....
i just wish some of the silent majority I receive E-M's from would for once
add their opinion to the exchange..... in the public forum.. but i don't think
Ray actually understands what his type of combative posts do to drive, what i
have seen, as some people with a very broad knowldge of optics, into not
posting just because of having to deal with someone like him....
He has told me how he has e-m's from this "od" that consider's my post as
uneducated and usually incorrect.... but I think that was a defensive knee jerk
reaction to help bolster his own opinion of himself........ (insert ha ha
here)......
When you let ignorence and hatred hinder your ability to communicate on a
educated and intelligent level this is what it deteriorates into, an
interjection of insults and rants and raves....
..(insert goose steps here)...with a swastika armband attached...
I for one am tired of always being on the defensive, trying to explain
something I have posted to someone that isn't really interested in the correct
answer... only interested in the thrill of the debate and being argumentative,
if he doesn't like your post he interjects questions, but when you answer those
questions as well, he just brings more things out of context and does not even
mention the answers that you gave to his question.... no affirmation
or even a reference to the information as a whole... i don't think i have even
seen in any of his post an agreement... even though the answer was correct.
i guess its just not his nature to ever be agreeable........
well enough said...end of thread
Jeff
Mike Tyner, OD
> but i don't think Ray actually understands what his type of combative posts
> with someone like him....
It's unfortunate that sci.med.vision is affected this way. I don't know
any other newsgroups that are so dominated by one layman.
Specs31
Dr. Mike wrote:
>It's unfortunate that sci.med.vision is affected this way. I don't know
>any other newsgroups that are so dominated by one layman.
i know that you don't have much of an opinion on my optical abilities,
which is fine by me, but you should run through deja one time and see the
amount of wasted bandwidth he has actually used up... and mostly doing the
things he has done in this thread... tis sad.
don't worry i've been informed how you so dislike my Ha Ha's so this is
one short and ha ha free posting.....
.. even though you don't consider my opinions or understanding of optics
worthwhile or of any use, atleast you did it through private channels and did
not waste reams of bandwidth like some unmentioned persons did....(insert name
here of guilty party)
though the respect doesn't go two ways ... i still learn from your
posts.. the one on migraines i found very interesting...just to name the
latest..
TaTa
Jeff Trail ... your local optical neanderthal (unrespected and
downcast)...but still hacking away :-)
Carl Seutter IV
Hi Ray,
I've snipped all of the crap. :)
Prism diopters are used because it works for the people who need to use such figures
better than anything else that has come down the pipes! We would have converted long
ago if the opposite were true. If you doubt my statement, try making a few pair of
glasses! All industries have their jargons that seem weird to other industries. I'm
suprised that you haven't figured this out yet! Just because it doesn't make sense
to someone who has never made a pair of spectacles in his life doesn't invalidate
the term!
Degrees of deviation works fine for mass production of camera lenses and specialty
items that are mass produced. It just doesn't jell when dealing with opthalmic
lenses!
The prism dipoter, ofr measuring prisms in opthalmic use, devised by Charles F.
Prentice, consists of measuring the deviation produced by the prism at a given
distance.
The prism diopter, symbol online "^", represents a displacement of 1cm at 1 m
distance. 2^ produces a displacement of of 2 cm at 1 meter distance.
For measuring prisms in opthalmic spectaclesthe Prentice or tangent scale is used.
This consists of a block(P) separated by a distance (x) meters from a scale(S). The
scale is divided into ^ units having a separation of X cms. The 0 point on the scale
consists of a longer line than the rest. The prism to be measured is placed against
the block (P) with it's face parallel to (S) and it's base toward the 0 end of the
scale. The 0 line is observed through the prism and it's position read with
reference to the scale observed outside the prism, the result being directly in ^ or
fractions thereof!
Most ^ measuring scales are made at a distance of 3,5, or 6 meters.
I'm sorry if this is alien to you. It is plain as day to anyone who has working in
opthalmic optics for a reasonable length of time. The use of ^D instead of degrees
deviation is because degrees are used for another function in spectacles! It is used
to position crossed prisms in polar coordinates!
The jargon serves it's purpose! It's to allow people to make spectacles individualy
tailored for each and every person. The terms you quote only work in factories that
mass produce one item at a time. <Mass producing of camera lenses for example>
Sorry! Reality knocks on the door! Until you can at least surface a simple OD +2.00
-75 x 45, OS -2.00 -.50 x 95, add OU 2.00 and make sure that the person can read
through the bifocal, stick to your profession!
We use the terms of measure that have stood the test of time, just like your
profession! I agree that some of them may be confusing to laypersons, but the
definitions work perfectly given the medium! I'd rather see clearly than use
definitions that do not apply!
Carl
Mike Tyner, OD
Specs31 wrote:
>
> i know that you don't have much of an opinion on my optical abilities,
Huh? If somebody has told you that, I think I've been misrepresented! If
I ever said anything to that effect, I'm sorry and I was wrong. I wouldn't
give you high marks for grammar or punctuation, but it's pretty obvious to
me that you know more about optical lab work than I ever will.
Who would tell you such a thing?
Specs31
carlmeister hacked out:
>Hi Ray,
>
>I've snipped all of the crap. :)
than whats left ??... :-)
> All industries have their jargons that seem weird to other industries. I'm
>suprised that you haven't figured this out yet!
He has... we are supposed to assimilate to the rest of the optical
trade....across the board..no matter if it astronomy, laser technology or
making sliding glass doors if it involves optics of any type than we must all
have the same degree(no pun intended)
of set rules and regulations...(wondering what the PD is on a sliding glass
door??)..never mind back to the post at hand ,but since we are supposed to be
in "borg" mode and no longer an indiviual industry unto our "breadcrumb roach
infested self" i guess we will all have to be retrained and assimulated into
the "big" picture....
>I'm sorry if this is alien to you. It is plain as day to anyone who has
>working in
>opthalmic optics for a reasonable length of time. The use of ^D instead of
>degrees
>deviation is because degrees are used for another function in spectacles! It
>is used
>to position crossed prisms in polar coordinates!
Ohh... i saw the new Alien movie this eve. ...never mind... and i hate it when
i lose the coordinates when i'm crossing the prism with a polar something or
another chomping at my tail end......:-)
>The jargon serves it's purpose! It's to allow people to make spectacles
>individualy
>tailored for each and every person. The terms you quote only work in
>factories that
>mass produce one item at a time.
Nix that...remember we are being assimulated... from now on no more cylinder
and we all are +2 sphere's and god forbid if you needed reading addition
>Reality knocks on the door!
it may knock but i think he won't answer... :-)
>Until you can at least surface a simple OD +2.00
>-75 x 45, OS -2.00 -.50 x 95, add OU 2.00 and make sure that the person can
>read
>through the bifocal, stick to your profession!
making sure to supply OC's and using the correct amount of decentration of
course....
>We use the terms of measure that have stood the test of time, just like your
>profession! I agree that some of them may be confusing to laypersons, but the
>definitions work perfectly given the medium! I'd rather see clearly than use
>definitions that do not apply!
And you expect this to be considered on a serious matter as this?? you know
we should retool every pc. of optical equipment we have in this "roach infested
area" to meet the new standards,.. and prentice??...chuck it out... use Rays
rule... " i don't understand how to do it or exactly how it relates to
optics.... but do it "
Carl, vernon stated some pretty good arguments but i think you kind of
bundled it all up in one posting..... DAMN GOOD POST... to bad he won't
actually read it and try to understand what you said... he will do, what i just
did in jest, with a malicious attempt to twist and slam your effort to educate
him....
Maybe he'll surprise us and actually show some type of respect and agree
with your post.....
on a postive note (which i see less of these days in this NG) i think
your post just about sums it up .... even though i maybe a lowly lab rat you
get a STANDING OVATION from this poster....
well said...and hopfully some people will read it and take it as it
should be taken...not mentioning names (rice a roni the san francisco treat)
TaTa
Jeff (sitting in the corner nibbling on bread crumbs)
Dennis Yelle
In article <19971130044...@ladder02.news.aol.com> spe...@aol.com (Specs31) writes:
[...]
>Ray is not the only
>contributer... maybe the most obscurant and the rudest but not the only one
>with an opinion....unless of course you are talking to him, than its his way or
>no way....
> am i the only person who has never seen Ray answer a question on optics in
>this group??
Well, I don't like Ray's style, and I don't like your style either, Jeff,
but I have seen Ray answer lots of questions asked here.
He has us given lots of URLs that he has found.
Maybe you didn't think those questions were about "optics".
But they were about "vision" and this is "sci.med.vision".
[...]
> He may consider my type of answering a post idiotic, which is fine with
>me. but atleast I try to be helpful and not just condescending
Not condescending??? Mr. hahaha not condescending?
Oh, I see, you said "not just condescending".
^^^^
I guess you think it is OK to add a condescending hahaha after every
other sentence in your "answers" to non-optical people. Postings that
contain exactly one upper case letter, the J in Jeff. You don't
do that when you talk to other optical people. I wonder why not.
[...]
> i just wish some of the silent majority I receive E-M's from would for once
>add their opinion to the exchange..... in the public forum..
OK. You got it Mr. Jeff hahaha.
>but i don't think
>Ray actually understands what his type of combative posts do to drive, what i
>have seen, as some people with a very broad knowldge of optics, into not
>posting just because of having to deal with someone like him....
Well, actually, I do agree with you about this.
With the posts from Ray and Mr. hahaha, who would want to stick around?
But, again, this is a _vision_ group, not an _optics_ group.
If you want an optics group, why don't you go find one?
> He has told me how he has e-m's from this "od" that consider's my post as
>uneducated and usually incorrect.... but I think that was a defensive knee jerk
>reaction to help bolster his own opinion of himself........ (insert ha ha
>here)......
When I see a posting filled with "....." and "ha ha ha" and lacking
a sufficent number of upper case characters, I think it was posted by
and uneducated person. What would you think if you saw a posting
like that from somebody else???
> When you let ignorence and hatred hinder your ability to communicate on a
>educated and intelligent level this is what it deteriorates into, an
>interjection of insults and rants and raves....
>..(insert goose steps here)...with a swastika armband attached...
I couldn't agree with you more, Jeff.
I am glad you are finally starting to see the light.
Dennis
--
den...@netcom.com (Dennis Yelle)
"You must do the thing you think you cannot do." -- Eleanor Roosevelt
Dr. P. Rozanec
>
>So why not be consistent, independent of the magnitudes used, Visual
>fields use both small and moderate angles. Would you advise their
>using prism diopters for small angles and degrees for large ones? I
>don't understand your angle, I guess.
>
By that argument, Fahrenheit and Celsius scales shouldn't coexist.
Peter
Specs31
>Not condescending??? Mr. hahaha not condescending?
>
>Oh, I see, you said "not just condescending".
Maybe you should look again at those posts... have I ever been insulting
when trying to answer a question placed here?? No, but i always tryed to keep
it on a lighthearted level while still answering the question.(to an original
post...not this follow up BS from Ray)
If I started in with using all the technicle jargon what would be gained??
Most people have already tried that route and had or have not gotten
satisfaction ... thats why they are posting a question here...
>With the posts from Ray and Mr. hahaha, who would want to stick around?
>But, again, this is a _vision_ group, not an _optics_ group.
>If you want an optics group, why don't you go find one?
Thats fine with me... you answer all the questions from now on and I'll watch
how far you are in the technicle department. Even though you dislike me , and
you may think my style of posting is idiotic, I have helped numerous people in
this group... besides the post of the original, usually the poster will E-m
back with a slew of follow up questions and wanting options... and as they get
to understand more and more of the reasons behind the problem and how it is
effected "optically" than I start to step up the amount of technicle
information. Sometimes I get no reply and in some responses it turned into a
regular marathon of E-m's.
Just because on a personal level you dislike me it doesn't really matter
to me. I don't know you and have no desire to know you and could really care
less about your opinions. But i'm not going to let someone like you, who are
one of the so called arm chair experts that sit back and have decided they know
everything about optics, run me out of this NG... you may have read some
articles on optics and absorbed some information but i'm postive there is alot
more you do not know about optics than you do know....
>When I see a posting filled with "....." and "ha ha ha" and lacking
>a sufficent number of upper case characters, I think it was posted by
>and uneducated person. What would you think if you saw a posting
>like that from somebody else???
If i asked a question about a subject and there were answers posted .. than I
would read them and see if they stand on merit... not based on what you
consider bad grammar or what was it "lacking in upper case letters"
Which i think is what most of them do, I try to answer the questions as a
whole and not just step into threads and pick apart a post and instead of
looking at the question and information as a whole look for a mistake and than
run a thread into the ground on the basis of "you may have got it right in 95%
of the information ..but ohh.. you didn't captalize this letter and ...you used
a double negative" ....
As for this thread (which i hope is coming to an end) after about the third
or fourth post the rest has just been a practice in optical training for
Vernon, Dr.Mike,Carl and myself.....
We each answered the question and even stated more than a couple of ways
that it can be done... But as the thread progressed we went into all types and
kinds of directions....
Lets list a few shall we.......
1) Went into two ways to convert it based on a 180 degree and a 360
degree basis...
2) Talked about visual fields
3) Touched on slabs and imbalnced power and how it effects the person to
focus in the near point
4) Prentice law and how prism induced would effect sight
5) Prism diopters as well as why we use the word diopter and how it
relates to the field of optics (optmetrics)
6) How lenometers are used ..
7) I think even some cross polarazation and talking about OC's and
power conversions got into this wild mix
Thats just some of it that I thought of off the top of me head...in
optics, some of the things that Ray so merrily dismissed time and again in this
thread is what we base all our optics on when dealing with optics in corrective
vision.....
You maynot think my contribution was up to your level in this group ..so
be it...I'm not here to impress you or even to consider your opinion. You are
always going to find fault with anything I post just because you look at it on
a personal level and not on the information itsself.
It doesn't really bother me in the least because you and Ray always look
at and respond to the posts not based on the problem of the question and
usually not even based on the answer is a whole... but you guys like to pick
out some little part and try to expand it into some big tragedy.
The saddest part is even when i see answers to post that were and are
correct all this BS detracts from the information that was provided., and worse
when you slash, burn or whatever you like to call it the posts we make , we
usually answer the questions that followed and than get ripped apart again.not
because of incorrect information ,but because you took it onto a personal level
, where no matter what i would or have said it was going to be wrong.I think
that you or Ray would probably have heart failure if you actually agree'd with
anything I said or learned anything.(and your fingers would revolt if you ever
tryed to post it)
You've already made up your mind that I do not know what I am talking
about in optics ...so make it easy on yourself....delete me or just don't read
any of my post....
I'll continue to actually help people and you can do whatever it is you
think you are getting done......
END OF
THREAD!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
jeff (<<---lower case.....ouch...revoke my ABO and NCLE).
Specs31
>I don't like your style either, Jeff,
>but I have seen Ray answer lots of questions asked here.
>He has us given lots of URLs that he has found.
>
>Maybe you didn't think those questions were about "optics".
>But they were about "vision" and this is "sci.med.vision".
Missed this one ...Sorry,
This maybe sci.med.vision.. and Ray post an opionion and asnwer in every
catogory... thats fine..so he's an expert in every field. Me??..... I know
visual optics... I don't answer the medical questions, leave it to the OD's and
OMD's....I read them and if it is something I don't know or find interesting
than i'll go do research on it... but what would be gained if i posted a bunch
of BS about something that is not my field of expertise??
I have no problem with anyone in this group (unlike some people i know) and
answer questions based on my knowledge of optics and how it relates to
corrective vision. There are times i have read posts that may fall under the
"medical" heading and spooted somethings that i thought were left out... but
the difference between me and people like you and Ray is i just E-m the Doc
directly and followed up...instead of doing what has been done in this
thread...
Mostly this whole thread was just a workout in optics that we all already
knew and Ray decided we were all incorrect, and now I guess you can be added to
the list......
Well... you tell me how to convert degree's to prism diopters?..but even
further how will the prism run (axi) and to what effect will it have??
You do that and really undersatnd exactly how it is done and why and the
effect it has on refraction... than you can lecture me...
Till than...<<delete>>
Oh well i guess we made it easy for you.....just copy and paste some of our
threads... but coping it down really doesn't mean you understand it and how it
relates or effects it physically...
Who knows maybe i do know atleast something about optics....I'm trying to
learn inbetween shoe sales.....gotta make a living somehow.....
Jeff
Carl Seutter IV
> Dr. Mike wrote:
>
> >It's unfortunate that sci.med.vision is affected this way. I don't know
> >any other newsgroups that are so dominated by one layman.
Are you referring to the layman Ray Chamberlain, or the journeyman Jeff Trails?
Carl
Mike Tyner, OD
> > >It's unfortunate that sci.med.vision is affected this way. I don't know
> > >any other newsgroups that are so dominated by one layman.
>
> Are you referring to the layman Ray Chamberlain, or the journeyman Jeff Trails?
Ray, of course. Jeff doesn't post maliciously.
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
...........
>
> BUT we are not talking about that facet of the optical industry ... only
>you could tie those things into a post having to do with vision and the three
>O's as you like to say....
Hey, Man, it was *YOU* who first stole the word 'optical' to cover
whatever territory you wanted to put under your and your buddies'
autocratic rule. ;-) 'Optical' refers to a lot more than the fun and
games of the "3 Os". Oh, oh, oh!!!
> thats almost as bad as lumping every engineer into a "same heading
>group"... you know as well as i do that a civil engineer and a electrical
>engineer are not going to be using the same terminoligy... your really reaching
>in this thread now.....
*You* did it, May; and *you* also told me this thread was *over* --
way back there! Sure, EEs don't use percent of grade, but they don't
use the word 'engineering' to refer only to what *they* do, either!
Let's confine what we're talking about here, Buddy.
>>You ain't a industry, Man, you's a cramped corner of a industry what
>>never got cleaned. Breadcrumbs and roaches everywhere.
>
> but this "cramped corner" is all in agreement on what prism is...and how it
>relates to our Bread crumb infested corner....
Hey, I hear noises for the roaches! I gotta get outta here, Man!
>>Then why would labs "spin out" if you gave them degrees (angular ones,
>>not academic ones) ?
>
> never said "labs" per say...
Hey, I like that "per say". It's time English took Latin and made it
'se' something!
>just certian people in the labs... not every
>lab understands optics... alot of them are the "take the order in and run it
>through the computer and than just do what the ticket says"..... but do they
>understand what they are doing??? ...sometimes yes...most of the time no...
>thats just the downside of being trained in a big lab compared to a small hands
>on lab ....
> i wish it were different myself and i see the wholesale business
>producing "optical" handicapped people every day....as things get more animated
>we get less and less of the people that understand what they are really doing
>on the "optics" level......
So take the incompetent people out of it and put in some good hardware
and software. I appreciate the concern here for quality work, but I
don't buy the across-the-board big-is-bad conclusion here, or that the
solution is to get rid of the big. Whatever the solution is to little
fish, when they start getting eaten by either scrupulous or
inscrupulous big fish, the solution for the biomass, or the top of the
food chain, is not necessarily to wipe out the big fish.
> if it was up to me i would make everyone in the optical
There you go again: "The optical". You're gonna make EEs use civil
engineer's double talk, right? You're gonna make the experimental
physicists at high-energy coherent light sources, such as LBNL in
Berkeley, quit measuring the bending of a light beam in a prism in
degrees and make them do it in prism diopters, right? You're gonna
make them all train in a smaller lab, a smaller world, such as one
that *you* understand, right?
>cross train...
>that includes OD's right down...
If you start from there, you're gonna end up pretty far down. ;-)
OK, I agree about the cross training. I went to an Ivy League
university (Cornell, in the days of vacuum tubes), but they gave me a
course by a li'l ol' vacuum-tube-manufacturing character who had us
pumping down collections of the real parts to vacuum tubes and making
them actually work. . .sometimes. Course, we also had theory classes.
Once, for a report-writing class, in which we had to talk before the
class (not my scene), I built a simple UHF oscillator circuit to
demostrate standing waves, as something to help me get through the
awkwardness of talking before a group. It went OK, but a professor
who taught me AC circuit theory heard about it and asked me how I
managed to build such a thing. I informed him that I simply threw it
together from a diagram in the Radio Amateurs' Handbook. Actually, it
was a long time before I could easily relate practice to theory, but
they actually do meet, both in the case of electricity and light. How
about that?!
>i took classes on refraction just so i could
>get a better understanding of thier side of the coin... and i make everyone
>that works for me cross train in production and sales... i think it makes for a
>more well rounded and educated dispenser/tech and the people who benifit most
>from this is the patient.... thats my concerns... could give a crap if you or
>anyone else agree's with me or not
We-e-e-l-l-l now, Sonny, ah been thinkin' maybe you should get a
little exposure to the rest o' that there *optical* field as a whole
-- outside o' the 3 Os -- maybe even outside o' the aligator patch.
Maybe you'd learn that those who know more about light than you use
the same darn stuff basically that you use. . .and furthermore, they
do it all without PRISM DIOPTERS. How 'bout that?!
>>The next thing you know Ha-Ha Man is in there tryin' ta tear up a
>>little flesh, 'cause things get awful boring in the lab after ya know
>>it all. And thus we get the whole 9 yards o' cloth, instead o' just a
>>thread.
>
> if you notice when i deal with someone other than a layman thier is no "ha
>ha"... when it comes to optics on this scale of conversation its time to put
>the ha ha's away ....
> and when i make a post i try to cover it ..not like some people who pick
>apart a post and drop "one liners" in it and expect to be taken on a serious
>note....
We come in with a 'ha' and you pass it off with a 'ha ha'.
> >retake on the initial post: It asks *how* to convert from one unit to
>>the other; it doesn't ask *whether* it can be done. Tyner correctly
>>told him how, but included a comment about the method's only holding
>>near zero. I then commented on that and went around with Tyner on
>>that. Then Vernon, admitting that it would likely be a bad move, dove
>>into the fray. Well, you know (unlike the original poster, who was
>>soon outta here with his answer) how these neighborhood free-for-alls
>>go:
>
> and the answer's that both of those Doc's posted were correct each covering
>slightly different aspects of the same problem.....
Whatever you wish to think about that, *you* misstated what the
original question was, in your last post.
>>The next thing you know Ha-Ha Man is in there tryin' ta tear up a
>>little flesh, 'cause things get awful boring in the lab after ya know
>>it all.
>
> first.. i never claimed to know it all..have i ever said i did??..nope...
>next, the post i made were giving the COS squared of the angle times the prism
>= horz. prism (180)
>the SIN squared of the angle times the prism = vert. prism (090
>
>is away to convert it....don't see any flesh being torn there?? maybe someones
>little ego got bumped.. but no flesh flying.
Can't make any sense out of those formulae. Don't even know what
you're trying to convert. Certainly not prism diopters to degrees or
v. v.
> when i try to post i like to explain it... not just one line it to
>death...... so if you say the whole "nine yards"... so be it.....you are not
>the only one reading this thread... so if you don't care if i'm right or wrong
If I didn't care if you were right or wrong, why would I post
anything?
>maybe someone else reading this thread will learn something...and thats why i
>come here to begin with... even if it kills you to atleast think about it...
>some of us actually care about what we do and are trying to improve the optical
>trade..... so if you think i'm an idiot thats fine by me.. i could care less..
>but if someone learns something in any of these "9 yard posts" as you prefer to
>call them than i have done something i set out to do
Some of your posts are quite informative, but some of them create
confusion. The indication is that you can produce very good quality
eyewear, and have high ethics, but that your means of communicating
what you do in doing your job suffer considerably and reek of your
despising larger worlds which encompass what you do and present it in
a more consistent and understandable manner.
>>Say, have you *read* the references I sent you after you asked for
>>them? Any questions
>
>not yet... ordered the back issue that you said it was in....takes two to three
>weeks to get here... unless you know where i can find it out on the web
>somewhere....
No. But you can find that journal issue in a medical or optometric
library or probably in some ophthalmic practitioners' hands.
>and as for questions??... thats the difference between me and
>you... i wouldn't think twice about asking anybody anything... thats how you
>learn..... sometimes it's easier to learn with your mouth shut and listen.. try
>it sometime...and maybe be or show alittle respect once in awhile.. when
>attacked people usually attack back....
>
>>You gotta get educated on what the "whole optical industry" really is,
>>Man. It ain't putting specs on flamingoes.
>
> in the way i deal with the "optics industry" it is... i'm not interested in
>optical engineering or optics as in lasers or any other field of optics thats
>out there.... i have enough trouble dealing with the optics that "puts specs on
>your face"... let alone trying to deal with it all on a grand scale ..as some
>people i know on here try to do... :-)
Well, then don't try to tell all this world what kind of pseudo-units
one has to use to make glasses, because it ain't so.
> have fun picking this apart... i left plenty of openings for your one
>liners.....
Hey, I was waiting for your parting philosophical one-liner. Where is
it? Are you getting them out of a book you have there? Don't think I
can sleep tonight without your usual parting philosophy. . .and *I'm*
not an insomniac.
Ray
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
.................
>
>Ray won't be happy until we change the scale on all existing phoropters and
>lensometers and other instruments.
>
>I'll change mine if he'll cover the cost.
Well, my kitty hasn't figured on that. However, if you get all your
buddies to agree to change all of theirs as well, maybe we can go to
the state legislatures and tell them that optoms have given up all
this stuff about wanting to try to cure everything from soup to nuts
in eye problems, and have decided to clean up their own original act
. . .and then maybe we can get the beladen taxpayer to put all the 3
Os and their collaborators into the actual real world of today --
which the Internet is currently repeatedly rubbing them against.
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
...............
>
>OMDs and ODs use degrees with visual fields. Fields instruments
>have a CURVED BOWL.
I gave up on curing you of your curved/flat distinction. It must be
genetic.
>We are not going to write a lens script using
>visual field info.
I guess that says it. The li'l ol' watchmakers said things like that
also.
>These are completely different endeavors.
Different endeavors but same environment. The customer needs
efficiency, not cultural artefacts.
>I think in your
>case you
>have or are considering trying to take advantage of a patch of the small
>remaining visual field in the "bad" eye. This would be one of the few times in
>my
>45+ yrs as optomer that degrees would have to be translated into Prism Diopter
>so
>the lab could process the lens.
Well, I'm not going to try to actually get someone to include this
added port hole in a prescription lens, but maybe your practice hasn't
been as broad as it might've been, and maybe you could've seen the
light from the right angle (in degrees, of course) sooner. ;-)
>I doubt if it would work. It would take a lot
>of retraining of your visual brain.
No problema. Well, not a real problem. We're not talking about the
front end of the visual cortex which has to get programmed early or
never. And we're not even talking about necessarily immediate
recognition of what's going on when there is a signal, from such a
port hole, of movement *somewhere*, other than in the normal natural
field. How *quickly* I could, at this age, understand what such a
signal would present to me, and how *much* of it how *precisely*, are
clearly questions up for experimental findings. But a little, a bit
late, would still be useful under some circumstances.
>Be interesting though. I fear you would be
>dealing with a lens 1" to 2" thicker on one edge than on the opposite! I don't
>where you would find a lens blank that thick.
Wasn't going to include it in a prescription lens and didn't want it
across more than about a 0.5 cm of the spectacle lens' area, in a
peripheral spot. Was merely going to *stick* it on.
>Seems you had an idea of power
>needed. (I translated thickness to inches for other listees but we use metric
>system
>Don't have to do that with my Mexican clientela and certainly not for Ray)
No hablo métrico, Señor Doctor.
>Years ago, and we still sometimes use a very large black cloth for taking
>fields. It has the degrees from the macula stitched in many concentric circles
>plus some other landmarks (blind spot).
Degrees?! Oh, such sacrilege!
>(ASIDE: In my office over half of the 8 to 13 yr olds are malingerers.
What's their motive? I thought kids didn't want to wear glasses.
>and also
>almost everyone who is trying to get compensation for some accident etc. There
>is a fairly simple test to prove malingering using this old non-computerized
>fields test.)
Shshsh! Don't let the cat out of the cloth.
>>So why not be consistent, independent of
>>the magnitudes used, Visual fields use both small and moderate angles.
>>Would you advise their using prism diopters for small angles and degrees for
>>large ones? I don't understand your angle, I guess.
>
>
>We are not going to be prescribing prism for those large angle squint cases.
>(Squint = strabismus and is 4 letters shorter)
>
>The surgeon will only be thinking in terms of degrees for corrective surgery.
>That is
>a whole different ball game.
>
>We generally cannot measure angle of strabismus with our "refracting etc"
>equipment. The location of a light reflected by the cornea gives us a good
>idea of
>the squint angle. Makes little difference to us if it is 25 or 30 degrees. We
>will handle
>the case the same be it one or the other. If we send patient to a surgeon he
>will have to use his skills in deciding how much to change the leverage of one
>or
>more of the six strong extraoccular muscles and/or some check ligaments.
Well, if your Mexican friends, scientists around the globe and
everyone in most countries can use variations on the meter to measure
from femtometers to terrameters, I think personal-opto-types ought to
be able to cover a couple of orders of magnitude with the same angular
measure that non-elves use.
>I had a patient, Ray hates for us to use that word, Sat.
When an optom has a patient, the patient can only have resulted from
the former's optometry.
>One of her complaints:
>seeing double times. Found she needed 2 BDOD. So to her lens prescription we
>add prism 1 BDOD and 1 BUOS. We split the prismatic effect between the two
>lenses for cosmetic reasons as well as the better optical quality with smaller
>prisms.
>
>Nuf for now.
Back later with more anecdotal refutation of science? ;-)
Ray
Specs31
Dennis Yelle WROTE:
>Yes, you have. Every time you put "ha ha ha" in the middle
>of your "answer" you are being both insulting and condescending.
>Obviously if you are giving a correct answer to a question that
>was asked honestly, you are showing that you know something that
>the questioner did not know. There is no need to laugh at them too.
>
....... Maybe you need to read the post more closely... I HAVE NEVER LAUGHED AT
anyone in a post... if you go back through every post, i'll bet you can not
find one time where i put those "ha ha" it was meant in a negative way.... and
i don't think they were taken that way either by the poster...
I have helped numerous people and usually they say just the opposite
you are saying ... they appreciated the help and the explanations were easy to
understand and not one, had a complaint about my sense of humor... other than
you!!..:-)
Optics doesn't have to be talked about in a serious manner all the
time and i feel it's easier most of the time getting an answer across by using
a little humor than coming off sounding like the Albert Einstein of the optical
world ... why go into alot of technicle jargan and theory when the only people
benifitting from the answer would be someone else that has an understanding of
optics and chances are knew the answer to begin with??
Ohh.. don't take me wrong I love spouting theory and getting in to
the mechanics of optics.. but i try to save the booorrrring stuff for fellow 3
O's.......
If you read all of this thread , all the optical stuff... not the long
winded chest puffing, crap... but the actual technicle stuff .... and how much
of it do you think that someone, other than some of the three O's(notice i said
SOME.. not all of us even know some of it :-)), understands it all and how it
relates to the problem being discussed?? You may know a few things here and
there... an example being you gave me the number to multiply to get degree's
converted to diopters... But than what??? how does it work??.. in what
direction does the prism run?? how is it translated into a grid layout ...base
in/out base up/down??
Sometimes just knowing a small part of the total answer isn't
enough to lecture people over there answers as a whole...
The rules of optics does not transfer from one part of it to another...
each facet of the optical world has it's own rules and theories and formula and
buzz words that go with it... trying to have rules that cross the board , as
Ray, wants to have is silly....
Read the post by Carl Seutter IV <cseu...@alaska.net>
Date: Sun, Nov 30, 1997 04:13 EST and i think he made some outstanding points
on the "why" it doesn't work......
Hopefully this thread has come to a optical conclusion...or should that
be illusion??..<<hee hee>
Just had to get that in... what would it be if i posted and didn't live
upto my usually "codescending" post style....as you put it :-)
TaTa,
Jeff
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
..............
>
>unless of course you are talking to him, than its his way or
>no way....
Look who's talking.
> He likes to say "its his right to correct us"
Find this quote in a post of mine and I'll give you a free eyeglass
case.
>
..........
>
> We all in are guilty of leaving out, every facet of an answer and in most
>cases, i see fellow "optical" people only expanding the previous post.... and
>by stringing a thread, by its end every combination is usually covered... along
>with Ray's attempts at humor and trying to show everyone how optically inept we
>are by pulling strings of text out of a post and trying to intertwine some
>verbal jousting of his own into the middle of it... which by the way has
>nothing to do with the answer to the originating post......
Hey, you have me all tied in knots. What with all these strings,
threads, twine, etc. -- this is a real rat's nest. It's not
a-cord-ing to Hoyle. Let's get back to optic-nerve *fibers* or some
other strung-out subject. Somebody here is giving us enough rope to
hang us all -- and we're all sure to dangle in purgatory.
> am i the only person who has never seen Ray answer a question on optics in
>this group?? he waits till we all do and than just interjects his brand of post
>into the thread, which is usually combative and insulting, but has no bearing
>on the thread as a whole.
Threads don't require bearings; you should use pulleys instead.
> He may consider my type of answering a post idiotic, which is fine with
>me. but atleast I try to be helpful and not just condescending ... but thats
>his style
>
> i have my own...
How would you describe that?
>as do all the rest of you that post....
>
> i just wish some of the silent majority I receive E-M's from would for once
>add their opinion to the exchange..... in the public forum.. but i don't think
>Ray actually understands what his type of combative posts do to drive, what i
>have seen, as some people with a very broad knowldge of optics, into not
>posting just because of having to deal with someone like him....
How about some *depth* of knowledge in optics taken to its *full*
breadth, not just limited to ophthalmic lens-blank tweaking?
> He has told me how he has e-m's from this "od" that consider's my post as
>uneducated and usually incorrect.... but I think that was a defensive knee jerk
>reaction to help bolster his own opinion of himself........ (insert ha ha
>here)......
I have quite a variety and I could post excerpts from them, but (even
;-) ) I don't think that would be in good taste. I thought the "sci"
came first, the "med" came second and the "vision" was that seen far
beyond one little lab in FL, US.
> When you let ignorence and hatred hinder your ability to communicate on a
>educated and intelligent level this is what it deteriorates into, an
>interjection of insults and rants and raves....
>..(insert goose steps here)...with a swastika armband attached...
Wha'dja say about rants 'n' raves?
> I for one am tired of always being on the defensive, trying to explain
>something I have posted to someone that isn't really interested in the correct
>answer... only interested in the thrill of the debate and being argumentative,
>if he doesn't like your post he interjects questions, but when you answer those
>questions as well, he just brings more things out of context and does not even
>mention the answers that you gave to his question.... no affirmation
>or even a reference to the information as a whole... i don't think i have even
>seen in any of his post an agreement... even though the answer was correct.
It shall be *you* who pronounce an answer correct, jawohl? Achtung!
Der Führer hat gesprochen!
> i guess its just not his nature to ever be agreeable........
>
> well enough said...end of thread
Wrong again! I see, at this time, some more articles there below this
one. When are you *ever* gonna be right? ;-)
Ray
Specs31
Ray continues his usual BS:
>>next, the post i made were giving the COS squared of the angle times the
>prism
>>= horz. prism (180)
>>the SIN squared of the angle times the prism = vert. prism (090
>Can't make any sense out of those formulae. Don't even know what
>you're trying to convert. Certainly not prism diopters to degrees or
>v. v.
You think that maybe , just besides converting it you have to be able to
know the direction of the prism?? ... so you converted it... now what?? you
just induce the prism any direction you feel like running it... if your happy
today than lets make it base up...or if your sad than lets make it base down
down..... i would think as close as you like to stick to being exact you would
have brought that up already.. knowing the amount of prism is only half the
answer....so i just stated the way to plot it out......
But than again what do i know...
Quote:"Puritanism: The haunting fear that someone, somewhere may be happy."
Jeff (tired of this thread....its a waste of time)
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
...........
>
>Why go to all that trouble.
You mean optoms don't have "1/2" an ounce of sense, so they have to
drum up new and confusing terminology instead?
REMEMBER THE AMOUNT OF PRISM NEEDED WAS DETERMINED
>USING A FLAT WALL.
You must be a member of the Flat Earth Society, flat whatever doesn't
have anything to do with it. The *only* thing that has *anything* to
do with it is the simple factor of approximately 1/2 (plus all the
confusion, to people outside your world, as to how it should relate to
'focal diopter' (it shouldn't)).
>Now why did you leave this part of my post out of your
>retort????????????????????????????????????????????????????????????????????
>??????????????????????????????????????????
By now I've included your comments about flatness in several posts.
Trigonometry is handled in middle school, as I recall, or at least in
high school. Must we review it here?
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
................
>
>So what! WE USE A FLAT WALL TO DETERMINE PRISM POWER NOT A CURVED WALL. and
>our prisms are very small, seldom over 5 prism diopters and
>generally under 2. Why do you ignore the FLAT testing wall??
Up against the wall, mother***! I guess I don't know how to further
explain this matter to someone with your outlook. Probably Mike Tyner
could. I think he knows that the issue here is one of conformance of
dimensionless units and *nothing* more (other than the mentioned
confusion by the choice of the ophthalmic term for the case of prism).
Do you not agree that the outside world is able to use degrees down
below the smallest optometric prescription for prism without any
trouble, whether they measure by some means that includes a flat wall,
a curved wall or no wall at all? Walnuts!
>Of course I know that physicists use degrees. We take optics for a year (at
>least
>we did 50 years ago at Ohio State) over in the physics department. At the
>blackboard every day tracing rays all over the place. And now I have to put up
>with another Ray que esta' chingui y chingui.
Maybe it takes longer for optometrist wannabes. ;-) The physics
school at Cornell diluted their freshman physics course for engineers
a good deal, but not as much as for the they gave to liberal artists.
I'm afraid to ask about that "chingui" stuff. My standard Spanish
dictionary would give simply 'annoyed' for 'chingado' in American
Spanish, but as I recall having heard it from Mexicans. . . I think
Vernon's trying to force me to buy a Mexican slang dictionary. Maybe
selling *books* is his real job these days and all the rest is just
history. ;-)
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
............
>
>No trouble with the trig & geom but writing the computer program so that
>the signs would come out correct is a little complicated.
Oh, for the life of me, how now do *signs* get into the act?! Why not
bring the phase of the moon into this alchemy? You always use the
*same* sign on the degrees as you use on the prism diopters; you just
stick in a factor of 1/2 (accurate enough for ophthalmic purposes).
Perhaps a pentagram would be a better sign to use, but I don't
understand any of that stuff. Sorry, I'm an ignoramus when it comes
to mysticism.
>Remember almost all
>scripts have a cylindrical component. The formulae get a little wild. The lens
>has to end up meeting many thickness requirements all around the edges and the
>center.
>The optical center has to end up in the correct place. Look at the crazy shapes
>
>frames have and being an engineer you should be able to imagine the amount of
>data input necessary to get an acceptable finished product.
>
>The lens grinder has to grind in prism on almost all jobs to get the optical
>center where it belongs. He sometimes might get by with using an extra large
>size
>finished lens but a plus lenses would be thicker than necessary and thus more
>unsightly and with more aberrations etc that come with thickness. By grinding
>prism he can move the optical center over several mm and calculate critical
>thickness to make a better looking job that passes the feds minimum thickness
>requirements for safety - but no thicker than necessary for good optics and
>best
>appearance.
>
>For the script in my other post of prism 1 BDOD and 1BUOS. Let's say the script
>is
>a plus 5 - to make it simple. (I'm not taking into consideration the frame nor
>patients eye separation (PD) )
As you noted, the confusion of this abbreviation, as I used it a
couple of times, is another good reason not to use the term 'prism
diopter'.
>To get the prism needed just decenter RT lens down 2mm and LT up 2mm.
Degrees and the factor of 1/2 in whatever formulae you feel get wild
will get you to exactly the same result. Are you trying to tell me I
could legitimately argue that American industry couldn't design what
it has and does without using feet and inches in place of meters? As
Mike mentioned, the only problem in switching units is a rather high
cost in the process of updating capital facilities and in education.
>And you want us to change to a curved exam wall!
I want you to realize, after reading Jeff's post, that all you have
here is the Berlin Wall -- apparently to try to preserve an endangered
species, namely the optometraurus not-so-rex. Y'know, if you Texans
didn't have that puny stream there to differentiate yourselves from
Mexico, you'd be building a wall there like California. Hey, like the
Chinese tried that and it failed completely, except as a tourist
attraction. The British or the Romans or somebody (OK, I never liked
history anyhow) also tried it, with only slightly more success. Maybe
the way to straighten (I wouldn't pun you, would I) out optoms is to
make them operate outside their little walls. Or, OK do it in a
rotunda, or a pentagon or on a Möbius strip or in a Klein bottle. Or
better yet, let the customer go do it on his computer, and you can
just go climb a wall of whatever radius of curvature suits your taste.
;-)
How long can a thread get before Internic cuts it off anyhow?
Ray (Then again, maybe we should watch out to whom we give degrees.)
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
...............
>
>Fresnel lenses are not ground
Oh, for cryin' out loud, now prism diopters go with grinding. Well,
you don't associate with such snobs, but non-ophthalmic types have
lenses *"ground"*, really computer-fabricated, according to recipes
given in degrees.
and the 30 deg was determined by fields test ,no?
No. This is 30 deg vertically from some peripheral point, say
diagonally about 25 deg out from the optical axis, in the inferior
temporal quadrant to the corresponding point in the superior temporal
quadrant. I think I really want more like 45 deg, but they don't
supply these stick-on jobbies with that much deflecting power. But
with a 0.5-cm, 30-deg-BU prism lenticule in the lower outward part of
my spectacles, while looking straight ahead, I should see, in the
still sighted (but dimming) portion of my upper quandrant, a glimpse
of any activity going on at about 3 ft below my horizon, 5 ft away. I
don't think you'd say that calculation resulted from a "fields test",
but it's crazy to worry about whether it did or didn't: it's just a
good old trig calculation, which is all angles in fields tests are
about, as well as angles in ocular prismatic refractive correction and
every single other angular application known to humankind, aliens,
superbeings and armadillos are about.
>Fresnel was a French engineer and physicist. He come up with this concept in
>early 1800's. The lenses were used for lighthouse beacons.
>
>The Optical Sciences Group of San Rafael, California about 30 yrs ago developed
>an adaptation of
>the Fresnel lens. The come in many powers up to 30 PRISM DIOPTERS. You better
>go and raise hell with that bunch!!!!!!
Are you tryin' ta tell me Fresnel sold *prism diopters* to lighthouse
keepers (or even light housekeepers)? My dictionary says Fresnel was
a *physicist*, not an engineer. He would've used degrees, and any
engineers designing lenses for lighthouses would've used degrees to
specify them, even French engineers. Even if, in the 1800s in France,
lighthouse keepers had to figure out prism diopters (without "needing"
them to get pupillary distance, except in the case, of course, of twin
lighthouses ;-) ), physicists and engineers today have about as much
use for prism diopters as lighthouse keepers had for cockroaches. And
besides, lighthouses have curved walls. ;-))))) However, in today's
world, lighthouses are like what optometrists are gonna be in
tomorrow's world -- replaced by the likes of radar, radio beacons etc.
The latter work at all angles, except the ones that try to preserve
what is obsolete. Though lighthouses died, Fresnel's brainy work
lives on, and if optometroublers can't solve problems with Fresnel
lenses without prism diopters, I guess engineers will just have to do
it. The latter don't get off the beam so easily. Ahoy, there, you're
headed for the rocks!
Ray
>They don't last very long since they are a thin plastic membrane.
>
>By the way how do they pronounce Fresnel out thataway. At OSU we weren't
>allowed to pronounce
>the "s" but in Texas I always hear it pronounced as if it were an English name.
>
>Vernon
>
>Ajúa (Ah HOO ah) is a Mexican low key yell of satisfaction. Forgot to answer
>that.
VernonH
In article <34847fbd...@news.sirius.com>, ra...@sirius.com (Raymond A.
Chamberlin) writes:
>No problema. Well, not a real problem. We're not talking about the
front
>end of the visual cortex which has to get programmed early or
never. And
>we're not even talking about necessarily immediate
recognition of what's
>going on when there is a signal, from such a
port hole, of movement
>*somewhere*, other than in the normal natural
field. How *quickly* I could,
>at this age, understand what such a
signal would present to me, and how
>*much* of it how *precisely*, are
clearly questions up for experimental
>findings. But a little, a bit
late, would still be useful under some
>circumstances.
Ray,
I wish a low vision expert would step in here. Meanwhile... In cases with only
a patch of vision in the periphery, somewhat like your one eye, I have heard of
devices
for deviating "straight ahead light" onto that live patch of retina. (These
are for those without a "good" eye) Then the brain has to understand that what
that peripheral area is seeing is really straight out in front of the eye.
Now in your case you are wanting to deviate light out there in the periphery
onto that
also out in the peripheral patch. You want it to be set up so a more useful
peripheral swatch of light ends up on your live patch of retina in that eye.
With the "good" eye going full blast I believe you will have a problem
processing what the "bad" eye might be noticing and where the heck what it
might be noticing
is.
What is the hold up in obtaining the Fresnel lens you mentioned and sticking it
on
your lens?? If it halfway works I would imagine that you would learn that it
would
have been better to have placed the image a little bit more this way or that.
Good luck!
Vernon
Raymond A. Chamberlin
Carl Seutter IV <cseu...@alaska.net> wrote:
>
...........
>
>Prism diopters are used because it works for the people who need to use such figures
>better than anything else that has come down the pipes!
A contentless statement similar to one claiming that better cars in
the future will only be built by using metric dimensions. At some
point, they'll all be built with metric dimensions, but only because
the meter has become standard, not because the inch was inferior.
>We would have converted long
>ago if the opposite were true. If you doubt my statement, try making a few pair of
>glasses!
That's like Dali saying all watches have to droop; if you doubt my
statement, try becoming a popular painter.
>All industries have their jargons that seem weird to other industries. I'm
>suprised that you haven't figured this out yet!
Gee whiz, I must be very stupid, right? But other industries don't
try to sustain themselves partly on the basis of such cultural
cutenesses, and even go so far as to say many of their functions
couldn't be done effectively without the happenstance of a confusing
dimensionless unit equal to approximately half of the unit commonly
used by the totally overwhelming rest of the world, including the much
larger portion of the optics industry outside of ophthalmics.
>Just because it doesn't make sense
>to someone who has never made a pair of spectacles in his life doesn't invalidate
>the term!
God, I should have to build a coliseum to find out what a cubit or
some of those other units were. My how logic abounds in optometry and
its worshippers!
>Degrees of deviation works fine for mass production of camera lenses and specialty
>items that are mass produced. It just doesn't jell when dealing with opthalmic
>lenses!
You find a physicist that will tell me that and I'll really be
puzzled. Aren't contact lenses mass-produced? If you can make some
of them stay positioned well enough to correct astigmatism, I don't
see why you can't make them handle some prism as well. Don't any of
them have prism? Whatever, your statement above is just plain
absurdly silly! What about the converse? Do you also believe that
mass-produced lenses for cameras could not be designed and fabricated
by using prism diopters in their beam-bending specifications rather
than degrees? Hey, when they start using get artificial crystalline
lenses, won't it "jell" there either. Well, OK, I wouldn't put any
prism at that point, but optometroopers and their fellow travelers get
funnier and funnier as they deflect. ;-)
>The prism dipoter, ofr measuring prisms in opthalmic use, devised by Charles F.
>Prentice, consists of measuring the deviation produced by the prism at a given
>distance.
Ah, so Prentice himself introduced this mysticism, simply to sell his
rule of thumb. That's like commercial outfits today getting streets
named after them that cross freeways, in order to get very large signs
on freeways to advertise their businesses. So why didn't Prentice
call his unit the 'prentice'; at least that wouldn't have confused
with focal diopters, which even measure a different dimension? (Even
if he had called it a 'dipoter', as you have, he would've better
blessed us. ;-) )
>The prism diopter, symbol online "^", represents a displacement of 1cm at 1 m
>distance. 2^ produces a displacement of of 2 cm at 1 meter distance.
>
>For measuring prisms in opthalmic spectaclesthe Prentice or tangent scale is used.
>This consists of a block(P) separated by a distance (x) meters from a scale(S). The
>scale is divided into ^ units having a separation of X cms. The 0 point on the scale
>consists of a longer line than the rest. The prism to be measured is placed against
>the block (P) with it's face parallel to (S) and it's base toward the 0 end of the
>scale. The 0 line is observed through the prism and it's position read with
>reference to the scale observed outside the prism, the result being directly in ^ or
>fractions thereof!
What exactly is the meaning of that '!'? Astounded at that point by
something? What is all that supposed to prove. One can proceed in
exactly the same way with a scale marked off in degrees, with degree
marks at approximately every 2 ^ marks, with "fractions thereof".
However, if you choose to build your x-cm scale continuing straight,
at right angles to the optical axis, as the angles get larger the
degree marks, of course, will not continue in an equidistant array.
Of course, if you ^-lovers really confine yourselves to the very small
angles Vernon claims you do, and you stick to tolerances that are
meaningful to your accomplishments, you'll never get out where a
normal cm scale will significantly deviate from a normal degree scale,
so you can simply modify your normal linear scale by a factor of 0.5
and mark it with degrees (and dissolve Prentice's copyright). But if
you want to live in the free world, and have your horizons opened to
the full continuous spectrum of reality, you might prefer a scale
beginning as normal to the optical axis and extending in a circular
arc, so as to maintain a linear scale in degrees on into larger angles
where the nonlinearity is significant in terms of functionality of
what you're trying to accomplish. This, of course, doesn't do damage
at all to your near-zero Prentice scale, so what are you screaming
about? You just want to keep your little world of farthings, pence,
shillings, pounds, guineas and whatever. Even the British gave that
scene up. One days Americans will give up inches, feet, yards and
miles. All of this hardly stimulates the intellect or worries glass
or plastic molecules, which will continue to behave as they always
have.
>Most ^ measuring scales are made at a distance of 3,5, or 6 meters.
>
>I'm sorry if this is alien to you.
It's simply dungeons and dragons and very poetic. . .but absolutely
silly.
>It is plain as day to anyone who has working in
>opthalmic optics for a reasonable length of time.
OK, so working in a house of lenses must be like working in a fun
house full of mirrors. After a while you get ve-e-e-e-rrrrrrrrrrry
funny.
>The use of ^D instead of degrees
>deviation is because degrees are used for another function in spectacles!
That's an absurd explanation! If I build a bathtub in feet and
inches, must I then measure the depth of the water in it in fathoms
. . .because I've already used up all my feet and inches? Hell,
according to your way of thinking, you could say, that I should only
use 'feet' to measure horizontal distance because tha'ts the way feet
walk normally. Then I must use 'legs' to measure vertical distance,
because legs stand upward. Takes all kinds, I guess. The Flat Earth
types refuse to believe in degrees. But they're also fading by
degrees. If they first got a straight science degree, instead of a
glasses-salesman degree, they might get off this arctangential
merry-go-straight-to-hell path.
>It is used
>to position crossed prisms in polar coordinates!
You mean *they* are? Well, using feet to measure distance along the
ground doesn't exempt my using them to measure the height of a tree.
That's the sort of thing that trigonometry is all about. Degrees are
used, by other than historically anomalous alchemists attempting to
blind the public, for *any* measurement of angles *any*where in the
universe at *any* orientation and of *any* nature. If you got an
angle, you got at least a fraction of a degree. Prentice be damned!
Who ever heard of Prentice and why should we care to? No angles ever
needed Prentice in the slightest. Prentice probably has a P. T.
Barnum outlook, or he would've found something better to do. ;-) If
an ophthalmic type can't use degrees for more than one sort of aspect
of spectacles or contact lenses, then that's his/her deficiency; the
rest of the world seems to have widely exercised their abilities to
use degrees for all the other angles in the universe. Even those who
use crooked angles come in various degrees, you know. The punishment
is supposed to fit the crime, so they say. Nobody seems yet, though,
to have figured out the right punishment for the deceptive use of
prism diopters. I'd say, "Throw 'em in prism," but for the fact that
there might be a worse punishment for cracking such sad and despicable
puns.
>The jargon serves it's purpose! It's to allow people to make spectacles individualy
>tailored for each and every person.
You misstate the purpose; it is to mysticize the simple in pursuit of
the need for and economic support of personal involvement in something
that, with computers, could be done much more cheaply and better,
certainly regardless of the units of any scale involved. Computers
need only think in terms of 0s and 1s, and when they play games, the
games are a little more complex than this silly one played by
optometrists.
>The terms you quote only work in factories that
>mass produce one item at a time. <Mass producing of camera lenses for example>
Hey, what's "mass produce one item at a time"? I always thought 'mass
production' meant you produce *lots* at a time. Whatever you meant by
this, do you really believe what you're throwing out here, not only to
me and those posting to this NG, but to all who search DejaNews,
AltaVista and other Usenet NG archives? It's really hilarious.
>Sorry! Reality knocks on the door! Until you can at least surface a simple OD +2.00
>-75 x 45, OS -2.00 -.50 x 95, add OU 2.00 and make sure that the person can read
>through the bifocal, stick to your profession!
Apparently, you believe reality depends on what profession you're in.
Well, yes, you can live in a sort of reality at the bottom of a well.
Ribid, ribid! But when the 'dozer fills it in, or the watchmaker's
cranny dissolves, that reality is somewhere at the other end of a
black hole.
>We use the terms of measure that have stood the test of time, just like your
>profession!
Hey, but as angles exceed the limits you impose on your mystical
small-angle dioptric world, time marches beyond such simple games.
But you've never told me the year Prentice (if he really was the one)
invented the prism diopter. The amount of time since that date is
probably very small compared to the length of time humankind has
recognized the universality of the measurement of angles, as done by
those who have other means of supporting their self-worth.
>I agree that some of them may be confusing to laypersons, but the
>definitions work perfectly given the medium!
Yep, all it takes is a good medium. . .with a good crystal ball. ;-)
Well, look hard. . .and see the time running out on prism diopters and
all such optometric nonsense.
>'d rather see clearly than use
>definitions that do not apply!
I don't think the problem here lies in the eyes. You ought to soon
see that you're defining the extinction of your trade. Actually, most
*optometrists* do; that's why most of them want to be miniature MDs.
Ray (Ya seen one angle, ya seen 'em all. New ones keep coming onto
the scene, but none of them ever is very impressive beyond 360 deg.,
which is right back where it started.) Tune in next week for the
difference between the units you must use for clockwise and
counterclockwise angles. I think this argument might come from a
similar group, one known as water witchers.
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>carlmeister hacked out:
>
>>Hi Ray,
>>
>>I've snipped all of the crap. :)
>
>
> than whats left ??... :-)
More crap. (However, would someone please slip a hint to Jeff that
'then' and 'than' are two different words. It's getting on my nerves.
Just kidding; I don't really have any nerves (except one good optic
nerve). ;-) )
>> All industries have their jargons that seem weird to other industries. I'm
>>suprised that you haven't figured this out yet!
>
> He has... we are supposed to assimilate to the rest of the optical
>trade....across the board..no matter if it astronomy, laser technology or
>making sliding glass doors if it involves optics of any type than we must all
>have the same degree(no pun intended)
>of set rules and regulations...(wondering what the PD is on a sliding glass
>door??)..
The PD doesn't stop at sliding glass doors; it just plows through with
guns drawn, so you better not throw stones at them if you live in a
house with sliding glass doors, Jeff. ;-)
>never mind back to the post at hand ,but since we are supposed to be
>in "borg" mode and no longer an indiviual industry unto our "breadcrumb roach
>infested self" i guess we will all have to be retrained and assimulated into
>the "big" picture....
Hey, maybe there's hope yet for the optomystically inclined (at
35.5 ^ ).
>>I'm sorry if this is alien to you. It is plain as day to anyone who has
>>working in
>>opthalmic optics for a reasonable length of time. The use of ^D instead of
>>degrees
>>deviation is because degrees are used for another function in spectacles! It
>>is used
>>to position crossed prisms in polar coordinates!
>
> Ohh... i saw the new Alien movie this eve. ...never mind... and i hate it when
>i lose the coordinates when i'm crossing the prism with a polar something or
>another chomping at my tail end......:-)
Hey, they have a place for those who lose their coordinates. You
better get your prism-made diopters together now.
>>The jargon serves it's purpose! It's to allow people to make spectacles
>>individualy
>>tailored for each and every person. The terms you quote only work in
>>factories that
>>mass produce one item at a time.
>
> Nix that...remember we are being assimulated... from now on no more cylinder
>and we all are +2 sphere's and god forbid if you needed reading addition
What? You're saying factories can't build toric lenses? Factories
with computers can build *any* kind of lenses, many more kinds than
elves in the back room can build. But, it's true. Factories have
trouble building individuals of endangered species. I guess we should
preserve them in bell jars somewhere. . .but not in *my* backyard.
>>Reality knocks on the door!
>
>it may knock but i think he won't answer... :-)
>
>
>>Until you can at least surface a simple OD +2.00
>>-75 x 45, OS -2.00 -.50 x 95, add OU 2.00 and make sure that the person can
>>read
>>through the bifocal, stick to your profession!
>
> making sure to supply OC's and using the correct amount of decentration of
>course....
All that. . .and MORE! *Digital* glasses! Programmable by Big
Brother. All those hiding out in Ocean Beach or wherever will see
what should be seen by upstanding citizens of the Force! We think you
need different OCs and centration, we'll wall-eye you and send your
foveae spiraling into a black hole. No more nonsense. You're in the
dumps, can't sleep -- your specs will show the world through
rose-colored glasses. Dial-a-reality! 20/0! +/-0.00 -/+0.00 x none!
0^ BI,O,U,D -- OD, OS, MD, PhD, DNA, DDT, etc. You wanna read a sky
chart while looking at an 8th-magnitude star? No problem, just slip
in the instant focus-switching program cartridge. You wanna see
what's around the corner of the building ready to whomp you. No
problema. Boomerang photons. Let Prentice and his ilk roll over in
their graves. They had their chance and blew it.
>>We use the terms of measure that have stood the test of time, just like your
>>profession! I agree that some of them may be confusing to laypersons, but the
>>definitions work perfectly given the medium! I'd rather see clearly than use
>>definitions that do not apply!
>
> And you expect this to be considered on a serious matter as this?? you know
>we should retool every pc. of optical equipment we have in this "roach infested
>area" to meet the new standards,.. and prentice??...chuck it out... use Rays
>rule... " i don't understand how to do it or exactly how it relates to
>optics.... but do it "
Go surfin', Man. We got computers to do it. They recalibrate much
easier than op-beat-their-own-tom-toms.
> Carl, vernon stated some pretty good arguments but i think you kind of
>bundled it all up in one posting..... DAMN GOOD POST... to bad he won't
>actually read it and try to understand what you said... he will do, what i just
>did in jest, with a malicious attempt to twist and slam your effort to educate
>him....
Wow! One crazy source of education! Come live in our well. You only
have to look up, 'cause that's the only direction there is any light.
An' it's a long way up, so prisms won't do you no good nohow.
> Maybe he'll surprise us and actually show some type of respect and agree
>with your post.....
Ah, the only type of respect to be shown to optotunists is agreement
with them. Nice concept. Has been tried before. To get everyone to
do it it takes a rather large army though, and some of the latter have
been known to defect. I'll even state it clearly: I don't see a
stitch of clothing on these emperors.
> on a postive note (which i see less of these days in this NG) i think
>your post just about sums it up .... even though i maybe a lowly lab rat you
>get a STANDING OVATION from this poster....
Well, us super-O-type optical beings must all stick together against
the impudent public who doesn't appreciate our idiosyncracies that
waste their money and confuse their eyes. Here and now, we shall form
a mutual admiration society. Clap, clap, clap!!!
> well said...and hopfully some people will read it and take it as it
>should be taken...not mentioning names (rice a roni the san francisco treat)
>
>TaTa
> Jeff (sitting in the corner nibbling on bread crumbs)
Let them eat cake! (But be sure to cut in into 60^ slices.)
Ray
>
Raymond A. Chamberlin
eye...@nospam.net (Dr. P. Rozanec) wrote:
>
............
>
>By that argument, Fahrenheit and Celsius scales shouldn't coexist.
Should we use Fahrenheit for low temperatures and Celsius for high
. . .or v. v.?
Ray
Raymond A. Chamberlin
eye...@nospam.net (Dr. P. Rozanec) wrote:
>
............
>
>By that argument, Fahrenheit and Celsius scales shouldn't coexist.
It goes without saying, of course, that optometric logic never ceases
to amaze me.
Ray
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
.............
>
> if you don't consider this optics than why don't you just leave this group
>alone......
The point is: I *do* very much consider ophthalmics to be part of
optics; that's why I think it should at least recognize and be
educated in scientific optics, if not practice something more
compatible with it -- instead of being "dioptometrically " opposed to
it.
> i'm tired of your bitching and moaning and how you like to change the
>threads around... now since you can't comprehend the use of the word diopters
>in what we were talking about... all at once now we all need to change to meet
>the rest of the so called "real" optical industry ....
>
> whatever... i'm tired of dealing with you... you are rude, and you can
>spout all your usual bullshit about how it is your "right to correct all of us
>optical idiots" and you can continue your oneline insults and all the rest....
>i'm sick of it.
>
> lets put this in a non optical term you can deal with piss off.....
>
> from now on find someone else to argue with.. you always take it on a
>personal attack and never do i see you discussing what the thread is about....
>you always wait till people answer than you just pick it all apart with stupid
>little one liners and unrelated things that were in the post that you usually
>lift out of context.....
>
> i've had enough....
Maybe the problem is: NG posting just isn't a good pursuit for
insomniacs.
Ray
Dennis Yelle
In article <19971202233...@ladder02.news.aol.com> spe...@aol.com (Specs31) writes:
>Dennis Yelle WROTE:
>
>>Yes, you have. Every time you put "ha ha ha" in the middle
>>of your "answer" you are being both insulting and condescending.
>>Obviously if you are giving a correct answer to a question that
>>was asked honestly, you are showing that you know something that
>>the questioner did not know. There is no need to laugh at them too.
>>
>
>....... Maybe you need to read the post more closely... I HAVE NEVER LAUGHED AT
>anyone in a post...
OK Jeff, if your "ha ha ha" is not laughter, what is it?
VernonH
>>(ASIDE: In my office over half of the 8 to 13 yr olds are
>malingerers.
What's their motive? I thought kids didn't want to wear
>glasses.
Ray,
That's why it is so unfair the way you compare the doctor's fixing or trying to
fix a patient's problem with that of a mechanic's fixing an automobile. And you
do not believe in an in-depth patient history!
Vernon
VernonH
>When an optom has a patient, the patient can only have resulted from
the>former's optometry.
*******
Flattery will get you nowhere
**********
>>One of her complaints:
>>seeing double times. Found she
>>needed 2 BDOD. So to her lens prescription we
>>add prism 1 BDOD and 1 BUOS.
>>We split the prismatic effect between the two
>>lenses for cosmetic reasons as
>>well as the better optical quality with smaller
>prisms.
>
>Nuf for>now.
Back later with more anecdotal refutation of science? ;-)
****************
Ray,
The above was to demo the language eye docs use.
Vernon
Specs31
>OK Jeff, if your "ha ha ha" is not laughter, what is it?
>
>
Same as you and Ray anf other people using the little :-).. when posting
sometimes things are taken the wrong way .. when someone is sitting and typing
a post they may type something in jest but without anyway of communicating it,
it all comes out the sameway..yes??... so if you post it and you say something
that is just thrown in as a lighthearted jesture and you do not show it you
think that possibly it maybe taken the wrong way?
I get tired of that little :-) so instead i use ha ha... what the hell is
the difference??....
forget it, this is just getting silly...here's going to be the new
answer... WHATEVER... you and Ray can try to figure out how to post a retort to
that and try to show how stupid i am....
Jeff
Specs31
Ray typed crap:
My reply.....whatever.
Jeff
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
>
......................
>
>It's unfortunate that sci.med.vision is affected this way. I don't know
>any other newsgroups that are so dominated by one layman.
I don't know any other NGs which are so misconceived as the property
of a single occupation or pair of them, quite independent of factual
and logical presentation of material.
Ray (Is anyone besides me experiencing a sort of a déją vu?)
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
.........
>
> i know that you don't have much of an opinion on my optical abilities,
>which is fine by me, but you should run through deja one time and see the
>amount of wasted bandwidth he has actually used up... and mostly doing the
>things he has done in this thread... tis sad.
> don't worry i've been informed how you so dislike my Ha Ha's so this is
>one short and ha ha free posting.....
>
> .. even though you don't consider my opinions or understanding of optics
>worthwhile or of any use, atleast you did it through private channels and did
>not waste reams of bandwidth like some unmentioned persons did....(insert name
>here of guilty party)
>
> though the respect doesn't go two ways ... i still learn from your
>posts.. the one on migraines i found very interesting...just to name the
>latest..
Once again you are wrong. You are tacking this onto the wrong party,
Jeff. You have no reason to tack this on Mike.
Ray
Raymond A. Chamberlin
"Mike Tyner, OD" <drm...@bham.com> wrote:
that Carl Seutter wrote:
>> Are you referring to the layman Ray Chamberlain, or the journeyman Jeff Trails?
>
>Ray, of course. Jeff doesn't post maliciously.
Maybe we should just leave Mutt. . .er. . .I mean. . .Mike and Jeff to
confuse each other ad infinitum. They seem like a natural perpetual
emotion machine.
Ray
VernonH
Ray,
I found an old reference work published in 1932 by Sir W. Stewart Duke-Elder.
After his name there are nine academic titles etc. Also Surgeon Oculist to H.M.
The King: plus 5 more jobs he held at that time. His six Tomes of over 1100
pages each
were the last word in Ophthalmology until probably the late 1950's.
In Volume One on his chapter on Geometric Optics he wrote....
..The tangent of "centune" or "prism diopters" (^ "delta sign) (of Prentice) is
the angle subtended by a verticle line of 1 cm, at 1 metre of distance: a prism
of this
strength gives an apparent deviation of 1cm. to an object 1 metre distant. (Fig
660)
Figure 660 is a diagram showing a tangent and also an arc to depict prism
"dipotres" and centrads. Also he has a Table comparing values of Centrads,
Prism Doptres, Degrees of deviation, Refracting angle of prism (in degrees).
As posted earlier in table from Troy Fannin's book on Clinical Optics
Duke-Elder
gives these values up to
100 centrads=155.54212 prism^.
60 centrads =68.33^.
but
40 centrads =42.28^
30 centrads =30.9^
A prescription seldom calls for more than 2 or 3 prism^. and even
5 centrads = 5.0042 prism^. Pretty darn close.
BUT since we test using a flat wall we dare not call the deviation centrads
because
it isn't. Otherwise since in ophthalmic optics we are dealing with small angles
and
thin lenses centrads can be considered to equal prism^ or vice versa.
But I fear if we threw away the prism^ concept some physicist or engineer will
chastise us "Hey, doc that damn wall is flat and you are calling the
measurement so
many centrads!!"
And Duke-Elder was an ophthalmologist.
SECOND PART
As I noted before prism grinding is done on almost every lens that has to be
surfaced by labs like mine or Jeff's..
The following is a simplification. A multifocal lens blank is thick and comes
with
parallel surfaces. There is no optical center (OC) yet. Depending on the script
1. the desired height of the bi(tri) focal seg.
2. the PD -(inter)pupillary distance of patient.
3. frame measurements
4. probably something else I've forgotten here.
All the above enter into how much prism to grind in which direction to put the
OC
where it should be.
If all the above comes out perfectly then the lenses have to be blocked
properly
for edging to insure that the OC ends up on the patient's face where the doc
wanted it.
Since this was about prism^ I didn't touch on controlling the thickness of the
lens. It is tied into the "power" formulae.
My point is that there are lots and lots of formulae to get the desired
results.
But the Jeffs will knock them out without too much sweat.
Vernon
Carl Seutter IV
Hey Vernon, Ray, and all watching,
I'm gonna do a bit of snipping, so if anyone is new to this thread, please look
back in this goup and even consult Dejanews if this doesn't make sense!
VernonH wrote:
> In article <34847fbd...@news.sirius.com>, ra...@sirius.com (Raymond A.
> Chamberlin) writes:
>
> >No problema. Well, not a real problem. We're not talking about the
> front
> >end of the visual cortex which has to get programmed early or
> never. And
> >we're not even talking about necessarily immediate
> recognition of what's
> >going on when there is a signal, from such a
> port hole, of movement
> >*somewhere*, other than in the normal natural
> field. How *quickly* I could,
> >at this age, understand what such a
> signal would present to me, and how
> >*much* of it how *precisely*, are
> clearly questions up for experimental
> >findings. But a little, a bit
> late, would still be useful under some
> >circumstances.
>
> Ray,
I find it hard to believe a brain can completely re-hardwire a large section of
itself in a reasonable timeframe at your age. Then again, I'm not a neurologist! I
can only speak on the optics of the lenses.
>
>
> I wish a low vision expert would step in here.
So do I! Such massive corrections are in the realm of low vision specialists. (then
again, he is seeing five of one of my posts! Sounds like abundant visions to me!
LOL <it's a joke, Ray>)
> Meanwhile... In cases with only
> a patch of vision in the periphery, somewhat like your one eye, I have heard of
> devices
> for deviating "straight ahead light" onto that live patch of retina. (These
> are for those without a "good" eye) Then the brain has to understand that what
> that peripheral area is seeing is really straight out in front of the eye.
This can be achieved considering the people I've worked with. I'm just getting into
low vision because of a few past patients that are regular patients of the doctors
I work with.
>
>
> Now in your case you are wanting to deviate light out there in the periphery
> onto that
> also out in the peripheral patch. You want it to be set up so a more useful
> peripheral swatch of light ends up on your live patch of retina in that eye.
A noble cause here! But can the bundle path survive the optics of the 20th
century? I tried to plot it with a Barium glass prism seg -1.00D, and it gave
dubious results. (Heck, when's the last time someone ordered a -D prism seg?) It's
possible to order one placed at the proper axis and degrees of deviation, but at
what cost and likelyhood of success?
>
>
> With the "good" eye going full blast I believe you will have a problem
> processing what the "bad" eye might be noticing and where the heck what it
> might be noticing
> is.
I've pondered this since the original post! The bad eye is getting an impulse that
is incoherent with the good eye. Hmm! Sounds like time may remove that deviation!
We've come full circle. Imagine someone walking down the street twitching like mad
because of conflicting visual signals. How long before the brain starts rejecting
the errant signals?
>
>
> What is the hold up in obtaining the Fresnel lens you mentioned and sticking it
> on
> your lens?? If it halfway works I would imagine that you would learn that it
> would
> have been better to have placed the image a little bit more this way or that.
>
> Good luck!
>
> Vernon
I also wish you good luck on the Fresnel experiment. I'd like to hear about the
outcome! I think that the lateral chromatic dispersion will render any image you
may recieve useless. I am open to new findings, however! If you want to further
science with this experiment, I'm sure we'll all wait for the results. <We are
third parties who have nothing to do with your decisions>
If you decide to try it, let me know!
Carl
KATELL
>>Ray, of course. Jeff doesn't post maliciously.
>
>Maybe we should just leave Mutt. . .er. . .I mean. . .Mike and Jeff to
>confuse each other ad infinitum. They seem like a natural perpetual
>emotion machine.
>
>Ray
Why not just give this up and get back to the real point of this newsgroup.
Why waste the time and space of those of us who really need help on visual
issues? If you want to "rag" on each other, write to each other personally,
not in this newsgroup. thank you.
Elaine Piegdon
"The day I don't learn something new is a wasted day."
Specs31
Elaine wrote:
>Why not just give this up and get back to the real point of this newsgroup.
It may seem like a waste to you but aloyt of the iformation that was
bouncing around in this thread was very informative..once you weeded out the BS
that is...
>Why waste the time and space of those of us who really need help on visual
>issues? If you want to "rag" on each other, write to each other personally,
>not in this newsgroup
Thats why the threads are labeled... just skip the ones you find stupid
and uninformative
but look at some of the things listed in that thread you found as a waste
of time.....
1. how to convert degree's to diopters
2. how to find the amount of diopters in direction base in/out
base up/down
3 prentice law (conveting distance/power to induced prism)
4 touched on power imbalance , prism and slabs
5 optical centers and decentration and what it does
6 fresnal prism
7 visual fields
8 decentration/segs multiple OC
9 inducing prism through decentraion or using prism rings
and i'm sure that even more could be listed ,but i just don't have the
time,
Sometimes if you dig through the fertilizer you find the roses.
Also besides these post, no others were being ignored .. I seen other
posts going on during this same time period. Thats what makes it nice.. even
though some threads need a bullet to head to put it out of misery , still you
can find piece's of great information in them ...(once you get past the rants
of raves...)
Plus it is a good way to weed the wanna be's from the ones that have the
know how to do it....
I figure Ray is just bored and enjoys a good argument.. if any of us said
white he would say black.....
Seems simple to me.. read the posts you find interesting and delete the
rest ... works for me.
Jeff
KATELL
> Seems simple to me.. read the posts you find interesting and delete the
>rest ... works for me.
>
> Jeff
Sorry. My apologies. I'll just continue to lurk.
Specs31
>Sorry. My apologies. I'll just continue to lurk.
>Elaine Piegdon
>
>"The day I don't learn something new is a wasted day."
no apologies needed... but just don't lurk.. we have alot of those types
already... don't let Ray be the cause of not getting in there and stomping
around like the rest of us.. what a better way to learn than hands on , down in
the trenches .. mud on your spec's posting ....
like they say.. "thiers never a dumb question.. just uneducated quiet
people"...
you have just as much a right to voice your opinion and thoughts as the
rest of us.. and if someone is posting and you want to know more...than throw
it out there... thats one thing this group is not short of... long winded
answers and people who just love to spout off about optics!! :-)
Jeff
Robert Shanbaum
Actually, Jeff, the normal method we use to move the PRP (prism reference
point) with Gerber generators is to decenter the back surface, rather than
tilting it (i.e., "grinding prism"). This method can be used whether there
is prescribed prism or not - we can tilt the back surface (to produce the
appropriate amount of prism) about a point, wherever we locate that point.
Blocking the lens on GC (blank geometric center) and decentering the back
surface to the PRP, and blocking the lens on PRP and not decentering it at
all, will produce exactly the same parts after generating on a CNC
generator. That's not absolutely true in every case with a cup-style
generator, inasmuch as they do not produce genuinely toric curves, though
given the curves and amounts of decentration that are typically ground, the
difference between lenses blocked on GC and those blocked on PRP after
generating on such machines will be unmeasurable using any tools normally
available in optical labs.
Regardless of the method used to move the PRP, the thickness characteristics
of the finished product will be exactly the same - unless one or both of the
techniques is performed improperly. It is simply impossible to change the
relative thicknesses around its periphery of a lens of a given index, power,
front curve(s), back curve(s), shape and size, without changing its prism
characteristics (or, if you prefer, without moving the PRP).
Specs31 wrote in message <19971205014...@ladder01.news.aol.com>...
>Vernon (still fighting a lost cause) wrote:
>>The following is a simplification. A multifocal lens blank is thick and
>>comes
>>with
>>parallel surfaces. There is no optical center (OC) yet. Depending on the
>>script
>>1. the desired height of the bi(tri) focal seg.
>>2. the PD -(inter)pupillary distance of patient.
>>3. frame measurements
>>4. probably something else I've forgotten here.
>>
>>All the above enter into how much prism to grind in which direction to put
>>the
>>OC
>>where it should be.
>>
>>If all the above comes out perfectly then the lenses have to be blocked
>>properly
>>for edging to insure that the OC ends up on the patient's face where the
doc
>>wanted it.
>>
>>Since this was about prism^ I didn't touch on controlling the thickness of
>>the
>>lens. It is tied into the "power" formulae.
>
> You think that is a little confusing... let me tell you a trick that is
>even more out of left field...shoot this one is from the parking lot next
>door..:-)
>
> There are two ways to surface a lens.... first, cut the lens on
center
>and use prism rings to locate the OC where we want.. second, is to decenter
the
>lens manually and cut it, say if the difference bwtween the near and the
>distant is 3 and i want a OC of 6 above the seg... lay it out 1.5mm in and
6
>down.. right...
> Now the fun stuff... say you are cutting a lens and you have
prescribed
>prism as well... something like 5 or 6 in (as an example) and a higher plus
..
>like a 4 or 5 sph. than taking into account eliptical error and
decentration ,
>if you layed it out say 5 and 5, than you're going to get some god awlful
prism
>ring like a 6.50 or 6.75.. right??... now the fun part... ignore this Ray
this
>is lab stuff (the things you think are idiotic)
> Instead of running it 5 and 5 and than letting the computer figure
out
>my decentraion (prism ring) to get the ground optical center in the right
place
>by the time it comes off the generator , i have come up with away to
cheat....
>I will do it wrong to get it to come out right!! <hee hee> ...
> This gets kinda complicated so hang onto your hmm hat..
> Instead of letting the computer figure it out for me i will take prentice
>rule and figure out with the power what a mm equals in induced prism with
this
>power (i know it cm .. but you convert it) well than instead of taking a
lens
>and if i cut it at 1.5 in and 6 down and 6 prism ring on the 180 (using the
>example) this would give me a very thick lens (nasal) considering you are
using
>a 6 ring in and on top of that a power of 5 (or whatever) so here's where I
>make it wrong but it comes out right by the time i mount the edged lens...
>using prentice rule I figure out the amount of mm to induce 1 diopter of
prism
>.. than instead of decentration and a large ring I will use the actual
lens to
>gain induced prism.... I'll mark the lens up at, say instead of 1.5 in
(half
>the mm between the distant /near)
> I'll lay it out at 0 or even go out..say a mm there by inducing prism by
>doing it wrong... and cut down the thickness of the ring needed.. down to a
2
>or 3 ring.... than when I get ready to edge the lens, decenter the bifocal
as
>normal and edge and mount it... now when i check it it will show the 5 or 6
>diopters of prism BUT I accomplished this by just using a 2 or 3 diopter
>ring... there by decreasing the thickness of the lens and if we are going
by
>the rough example than that would translate to around 6 mm of edge
thickness!!
>now thats alot...specially for the guy wearing them!
>
> Sometimes doing it wrong during the process to get it to come out
right
>in the end is well worth the trouble... I have alot of doc's in the area
that
>,even have thier own labs, that will just send me the prism work because I
get
>it to come out so thin...
>
> Used to try to show the guys that work for me this all the time but
they
>usually get lost in all the math.. but if you get a good grasp of the
basics of
>it than the difference it makes is great... as it is now I just go back and
do
>the math and block it and run it myself everytime (got to get dirty once in
>awhile ya know)
>
> I don't think I met anyone else that is doing it this way.. but
when
>they compare my prism job to someone elses the all ask how to do it.. :-)
>sometimes I get a 6 to 8 mm edge thickness difference between my lens and
the
>patients previous lens.. even if the RX and or the prism increased....
>
> I guess this is a little off the topic but ,hey ya gotta share
some
>inside stuff..... I'll be glad to explain it furher.. if something just
don't
>fall into place... (for a small fee of course!! ) :-)
>
> An apology to the people reading this thread that found this to
>boooorrrinngg... but hey the other fireworks from the previous posts in
this
>thread should make up for it!!
>
> TaTa.....
> Jeff ( still a shoe salesman wanting to be a optical person
someday... )
>
Specs31
>Robert Shanbaum wrote:
>we use to move the PRP (prism reference
>point) with Gerber generators is to decenter the back surface, rather than
>tilting it (i.e., "grinding prism"). This method can be used whether there
>is prescribed prism or not - we can tilt the back surface (to produce the
>appropriate amount of prism)
I've used gerbers. but more or less it's doing the same thing but instead
of the old fashioned prism ring you are doing it with the generator...same
principal, different method
>Regardless of the method used to move the PRP, the thickness
characteristics
>of the finished product will be exactly the same - unless one or both of the
>techniques is performed improperly. It is simply impossible to change the
>relative thicknesses around its periphery of a lens of a given index, power,
Right.. but i don't think you get what I'm saying...I'm talking about mixing
the two methods... manual decentration at blocking and using rings.... A
gerber when run is doing the samething the old generators did like the 2113 or
the 108 (etc etc etc ) but instead of tiltiing the whole lens you cut the angle
in just the back surface... so of course the thickness would be the same...
well not the same as a lens done with compensated prism software with rings...
anytime you block on center you get a thinner cut... but what i'm saying is you
mix the two... you have tilt through using prism rings and also through
decentration... so you get a thinner edge but the same anount of prism.... it's
easy as pie to demonstrate, run a + 5 with 5 base in than run it the way I am
talking about and it will be thinner....I've been doing it for years and it is
always thinner and noticably so, when you let the computer plot it out it
figures it on one plane and inducing the amount of tilt to the whole surface to
get the end refernce point to cross at the wanted point and still maintain
cutout thickness.. right??... well if I run that same RX through RXPlll and
tell it the layout I want and the BOC and when it says prism decentration click
"no" it will still give me prism rings for the prism .
Thats where the cheating comes into the picture.... by even giving it more
decentration in (instead of blocking on center) I let the actual lens give its
self prism and than cut down on the rings to make up the difference. There by
getting a thinner edge everytime....
The computers and generators can only figure out thickness and
decentration by the numbers you plug into the system.. so you are stuck with
the end result.. well I'm doing something that isn't listed as an option in
RXPlll so I just figured out away that makes it just a little smarter than the
software !! :-)
Most people use the same argument you are using and than when we run the
same job (power,frame,prism, etc etc etc) my lens will always come out thinner
and checkout the same in the lensometer as thiers... and I still have guys that
say I'm wrong.. even though the job is right there in the hand and mine is
exactly the same in power prism PD etc etc etc ... but thinner.
If you havn't tried it than how do you know it won't work??.. and I
never try to let a generator be smarter then me when it comes to understanding
optics!! LOL ... Sometimes we get to where we depend on the software and the
hardware to much and think just because the ticket says this, than thats just
the way it is and is the only way to do it...
just to prove the point that thickness can be effected by other
factors.... run a job a few different ways
ex: +4 -.50 x180 (54x18 48 57 ) run it with prism compensating
and layed out 5 in 5 down
. ex: +4 -.50 x180 (54x18 48 57 ) but this time on center
ex: +4 -.50 x180 (54x18 48 57 ) this time 1.5 in and 5 down
........
Enter in the BOC as 5 above ...... even though the same power is
involved and every measurment is the same I bet you get three different center
thickness's . So if that can effect thickness why can't my formula do it as
well?? Well I already know it can I've been doing it for to long to be told it
doesn't :-)
Don't knock it till ya tried it... and isn't it better to learn something new
than to just dismiss it as " that won't work.. my computer says so"..:-)
Oh well it's just a little exercise in mathmatics that most people tell
me I'm wrong.. but I'll just keep doig it the way i have been and everyone else
can do it thier way... I just thought i would throw it out there to anyone that
wanted to tinker with it ....
Have a happy holiday....
Jeff
VernonH
Subj: Re: CLs for colorblindness
Date: 97-12-05 19:30:04 EST
From: a...@brunnet.net (AIBrown)
To: Ver...@AOL.COM
Dear Sir;
I have seen no formal information on these lenses in soft material but I
have used such a lens for my patients for many years. For various reasons
we could not use a PMMA or RGP lens so decided to experiment and ended up
having a
local contact lens lab custom-make a HEMA lens with a red tint over a
central 7-8 mm zone. It has worked so well that we have used it for people
who do not need a prescription for vision as well as for people wearing
contact lenses for vision correction .
I have seen price lists from several custom lens manufacturing labs now that
offer this product listed under their tints as a "ruby tint". I have no
doubt that this is as available in your neck of the woods as here. Sorry I
couldn't be of more help.
Arnold Brown, OD
Saint John, NB, Canada
Waterloo '77
VernonH
Subj: Re: CLs for colorblindness
From: dr....@worldnet.att.net (Michael J Fleming)
To: Ver...@aol.com
Vernon:
Steve could easily find a x-chrome lens in the US. Kontour is a
manufacturer that comes to mind with SCL's. Adventures in Colors in
Colorado is another custom tinting lab which could pull through. Many
RGP labs still offer the x-chrome as well. Does this really improve
color vision? I'm unconvinced. Michael
Ver...@aol.com wrote:
>
> Listees,
>
> Maybe someone could help this poster (sci.med.vision)
>
> Vernon Hammond
> McAllen, TX
> OSU 52
> _______________________
> Subject: Correcting colorblindness repost.
BillyFish
To what extent can color filters help the problem of color blindness? What is
the theory behind them? My guess would be that the big effect will be to
reduce the information going to the eye. That is, if someone possesses only
two kinds of color receptors, any filter that does any good would cause the
light absorbed by at least one of the receptor types to be greatly reduce. Is
this reduction in information capacity helpful?
William Buchman
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
..........
>
> You think that maybe , just besides converting it you have to be able to
>know the direction of the prism?? ... so you converted it... now what?? you
>just induce the prism any direction you feel like running it... if your happy
>today than lets make it base up...or if your sad than lets make it base down
>down..... i would think as close as you like to stick to being exact you would
>have brought that up already.. knowing the amount of prism is only half the
>answer....so i just stated the way to plot it out......
It goes with out saying -- that you know which direction you want the
image bent in. If you don't know, you shouldn't bend it in *any*
direction. You don't have to figure the direction out mathematically
-- if that's what you're trying to do.
> But than again what do i know...
Beats me. No, you basically know what you're doing, but it's not
often you can explain it worth a darn. (And I do wish you would use
'then' instead of 'than' when it's appropriate. That wouldn't cramp
your style *too* much, would it? But "than" again, maybe that's just
your Floridian drawl. What do I know? Not even a 'thang' or two.
;-) )
>Quote:"Puritanism: The haunting fear that someone, somewhere may be happy."
Ho ho ho.
>Jeff (tired of this thread....its a waste of time)
Well, surely the "King of Florida" can proclaim the end of a thread
and enforce it, right? The next poster to this thread gets thrown to
the alligators.
Ray
Raymond A. Chamberlin
den...@netcom.com (Dennis Yelle) wrote:
>
..............
>
>OK Jeff, if your "ha ha ha" is not laughter, what is it?
I have to say that I don't really think Jeff was meaning to insult
people with those "ha ha"s. I saw them as just a kind of nervous
habit. He ought to realize that, in the quantity he used them, they
became pretty silly after a while though. But he's built upon quite a
level of independence of just about every outside influence, it seems
to me.
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>
............
>
>I wish a low vision expert would step in here. Meanwhile... In cases with only
>a patch of vision in the periphery, somewhat like your one eye, I have heard of
>devices
>for deviating "straight ahead light" onto that live patch of retina. (These
>are for those without a "good" eye) Then the brain has to understand that what
>that peripheral area is seeing is really straight out in front of the eye.
Well, that's, I guess, one of the applications of Inwave Optics
glasses, the Web pages for which I once downloaded. Presently their
server at:
http://inwave.com/optics/welcome.html
seems to be down.
>Now in your case you are wanting to deviate light out there in the periphery
>onto that
>also out in the peripheral patch. You want it to be set up so a more useful
>peripheral swatch of light ends up on your live patch of retina in that eye.
>
>With the "good" eye going full blast I believe you will have a problem
>processing what the "bad" eye might be noticing and where the heck what it
>might be noticing
>is.
Naw, most of the time I'll be ignoring what that small port from the
bad eye is showing. It will be just like rear-view mirror mounted on
my glasses. One knows categorically what the content of such a mirror
relates to and doesn't try to integrate it into the rest of one's
forward view. I'll just be catching any motion there, and if I
quickly sense it to be significant (like someone overtaking me
walking, at a time when I'm moving to the left), I'll quickly turn my
head (maybe while shying to the right) to directly see what the
movement is about.
>What is the hold up in obtaining the Fresnel lens you mentioned and sticking it
>on
>your lens??
Well, I only found out a week ago where I could presumably get such a
Fresnel *prism* (not lens). Since the place, in AZ, didn't list an
e-mail address, I sent a post card asking the exact price, including
shipping. No answer yet, so I'll call tomorrow. I still wonder,
though, whether they'll sell me this lens directly, since I don't have
any of those funny little letters after my name. ;-)
>If it halfway works I would imagine that you would learn that it
>would
>have been better to have placed the image a little bit more this way or that.
Could be. I can move it around, but the deflection angle I'm getting
is the max, so if I need more angle, tough luck.
Ray
Raymond A. Chamberlin
Carl Seutter IV <cseu...@alaska.net> wrote:
>
.................
>
>I find it hard to believe a brain can completely re-hardwire a large section of
>itself in a reasonable timeframe at your age. Then again, I'm not a neurologist! I
>can only speak on the optics of the lenses.
Read the post above that I just added. People here are tripping
really out of perspective. When you look into a rear-view mirror,
you're not retraining your brain. What I would be doing in using this
prismatic lenticule would be essentially the same thing.
>So do I! Such massive corrections are in the realm of low vision specialists.
Man, do these eye types worship their gods as controlling entities of
the universe! I'm just afraid that opticians really have to try to
comprehend that other people understand the world to just a little bit
more depth than they do and don't have to keep praying to the gods of
light all the time.
>
.............
>
>A noble cause here! But can the bundle path survive the optics of the 20th
>century? I tried to plot it with a Barium glass prism seg -1.00D, and it gave
>dubious results. (Heck, when's the last time someone ordered a -D prism seg?) It's
>possible to order one placed at the proper axis and degrees of deviation, but at
>what cost and likelyhood of success?
Don't know what all that mumbo jumbo is. Quite irrelevant though.
>
..................
>
>I've pondered this since the original post! The bad eye is getting an impulse that
>is incoherent with the good eye. Hmm! Sounds like time may remove that deviation!
>We've come full circle. Imagine someone walking down the street twitching like mad
>because of conflicting visual signals. How long before the brain starts rejecting
>the errant signals?
Really! Did you ever drive a car? Did your brain ever get upset from
looking into a rear-view mirror -- other than when seeing red lights
or a vehicle ready to plow into, that is? What I propose is basically
no different -- certainly not a neurological catastrophy or miracle --
just a little periscoping.
>
..........
>
>I also wish you good luck on the Fresnel experiment. I'd like to hear about the
>outcome! I think that the lateral chromatic dispersion will render any image you
>may recieve useless.
God, if that apple that was about to hit Newton's head had seen your
head before it instead, I'm sure it would've done a couple quick
right-angle maneuvers and stayed the hell away from your noggin in
fear of the future of gravity!
>I am open to new findings, however! If you want to further
>science with this experiment, I'm sure we'll all wait for the results.
Well, that wasn't exactly the idea -- and it sounds more and more like
I should keep the result a secret from you and Vernon, for fear all
the laws of physics will get written in neuro-opticalese. The idea
was not to further science at all. After all, people have looked
through prisms in all directions for half a millennium (hey, got all
those double letters in there this time) without changing science --
or even anything significant in their brains. Of course, those who
have worn inverting prisms constantly, over their full field of view,
have retrained their brains to see the world as it would appear upside
down without the prisms, and then retrained their brains to reinvert
the world after removing the prisms -- but that's an entirely
different trip -- like aspirin and LSD (or maybe Vernon goes down
there and tries those peyote caps ;-) ).
><We are
>third parties who have nothing to do with your decisions>
Well, if I run into somebody while wearing the prisms, I might sue you
for confusing the issue. ;-)
>If you decide to try it, let me know!
I already *did* decide to try it and you have already been let known.
Ray (slightly deviated OS)
Raymond A. Chamberlin
den...@netcom.com (Dennis Yelle) wrote:
>
...............
>
>OK Jeff, if your "ha ha ha" is not laughter, what is it?
>
>--
>den...@netcom.com (Dennis Yelle)
>"You must do the thing you think you cannot do." -- Eleanor Roosevelt
It's sorta like that Eleanor Roosevelt quote. After the umpteenth
time you've seen it, it's sort of a drag.
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>In article <34847fbd...@news.sirius.com>, ra...@sirius.com (Raymond A.
>Chamberlin) writes:
>
>>>(ASIDE: In my office over half of the 8 to 13 yr olds are
>>malingerers.
>
>What's their motive? I thought kids didn't want to wear
>>glasses.
>
>Ray,
>
>That's why it is so unfair the way you compare the doctor's fixing or trying to
>fix a patient's problem with that of a mechanic's fixing an automobile. And you
>do not believe in an in-depth patient history!
All these people in this NG are always crying. What are you crying
about now? How did we get from my question here to your sense of my
unfairness in an unrelated comparison anyhow? I think you're
basically demonstrating my fundamental complaint about health-care
providers (or would-be ones) -- that they're usually offering an
opportunity for their client to fulfill their need for emotional
satisfaction of their self-worth, rather than a skilled fix to the
client's problem. In my life I've heard numerous complaints from auto
mechanics and TV repairmen as to how unfairly health-care people apply
a double standard to *their* work. I have to say that I think your
complaint of unfairness is quite unfair. And you wouldn't give the
answers ahead of time to a fortune teller, now would you? Then why
should you do that with any *other* kind of diagnoser? People should
demand that they pay only for something new and useful. Those that
want to go to church and put money into a collection -- fine; but
that's not what human-body fixing and human-physical-function
supplementation should amount to. Refusal to submit to the objective
tenets of common sense and science in selling such well-delimited
services is the most fundamental of unfairness. But I still don't
know what all this has to do with your objection to my question
regarding kids you say are malingering. . .except that you realize
your use of "most" is clearly an exaggeration. And really, I doubt
that *any* of them are malingering. In any case, you seem to have no
answer to my question -- only a whimper about other things I've said.
Don't want the ceiling of the Systine Chapel; just want the side of my
house painted.
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>In article <34847fbd...@news.sirius.com>, ra...@sirius.com (Raymond A.
>Chamberlin) writes:
>
>>When an optom has a patient, the patient can only have resulted from
>the>former's optometry.
>
>*******
>Flattery will get you nowhere
>**********
My dictionary says for 'patient', "one under medical treatment." If I
am healthy and not seeing a physician for anything but go to an
optometrist for a pair of spectacles or maybe even just to find out
whether I need them or not because some propaganda from an optometrist
scared me into it ;-), am I "under medical treatment?" NO, NO, NO!
Optometrists are just MD wannabes. They misuse the word 'patient'.
They misuse the word 'prescription' -- by arranging to have the state
legislatures outlaw most types of glasses that would be cheap when off
the shelf, on the basis of the feigned parallelity of a harmless
refractive "prescription" to that of a pharmaceutical prescription for
a substance that can likely be dangerously used by the consumer.
Should a lawyer also call his/her client a 'patient'? Should a
beautician? Should a taylor? Should a physical trainer? I guess you
claim 'logic' is a nasty word, but I say, "Get logical, Man!" Yeah,
but what it's all about is very clear. These other people have to
deal with their clients as persons in full capacity for dealing with
the transaction. Optometrists -- not to mention physicians, some of
whose clients physically *can't" so function -- don't *want* their
clients to act in full capacity in dealing with the transaction. So,
I guess it becomes "unfair" to optometrists, again, for clients of
theirs not to consider themselves *patients*. How dare they?! Ah,
yes, the hand reaches out only in kindness. . . Cut the mush! We're
simply bending light through plastic! It either bends the right way
or it doesn't. It may be "unfair" to the seeker of worship for a
healer-shaman, but it's just another ear horn, toothbrush, comb, shoe
or even belt buckle. Maybe those seeking shoes that are too small are
also "malingering" or doing some other things that only "patients" do.
But we'll never know, because shoe salesmen, unlike glasses salesmen,
don't call themselves 'doctor' and don't take long histories of their
clients (so they don't have to spin their neurons like fortune
tellers). ;-) "Medical treatment". . .my a**! Impatient forever!
Ray (Optometrist, focus on thyself.)
>
...........
>
Ray
Raymond A. Chamberlin
ver...@aol.com (VernonH) wrote:
>Ray,
>
>I found an old reference work published in 1932 by Sir W. Stewart Duke-Elder.
>After his name there are nine academic titles etc. Also Surgeon Oculist to H.M.
>The King: plus 5 more jobs he held at that time. His six Tomes of over 1100
>pages each
>were the last word in Ophthalmology until probably the late 1950's.
>
>In Volume One on his chapter on Geometric Optics he wrote....
>
>..The tangent of "centune" or "prism diopters" (^ "delta sign) (of Prentice) is
>the angle subtended by a verticle
Did he spell it that way?
>line of 1 cm, at 1 metre of distance: a prism
>of this
>strength gives an apparent deviation of 1cm. to an object 1 metre distant. (Fig
>660)
>
>Figure 660 is a diagram showing a tangent and also an arc to depict prism
>"dipotres" and centrads. Also he has a Table comparing values of Centrads,
>Prism Doptres,
Are these different?
>Degrees of deviation, Refracting angle of prism (in degrees).
Are *these* different?
>As posted earlier in table from Troy Fannin's book on Clinical Optics
>Duke-Elder
>gives these values up to
>
>100 centrads=155.54212 prism^.
> 60 centrads =68.33^.
> but
> 40 centrads =42.28^
> 30 centrads =30.9^
So I take it a centrad is measured on a linear scale on an arc and
thus is linearly convertible to degrees.
>A prescription seldom calls for more than 2 or 3 prism^. and even
>5 centrads = 5.0042 prism^. Pretty darn close.
>
>BUT since we test using a flat wall we dare not call the deviation centrads
>because
>it isn't.
My we're suddenly fussy! You know damn well you call it prism
diopters simply because your granfathers called it that, not because
you ever worried about the fourth decimal place. *Engineers* don't
even worry about more than three decimal places.
>Otherwise since in ophthalmic optics we are dealing with small angles
>and
>thin lenses centrads can be considered to equal prism^ or vice versa.
>
>But I fear if we threw away the prism^ concept some physicist or engineer will
>chastise us "Hey, doc that damn wall is flat and you are calling the
>measurement so
>many centrads!!"
Why do you keep harping on what you know is pure nonsense?! Forget
the centrads *and* the prism diopters and simply state the number of
degrees, as everyone else does for *every* kind of angle. It's so
many degrees, even if you have a corrugated elliptical wall with
three-dimensional topographical tapestries on it. It's *not* the
*wall* that make the measurement, it's the deflection. The deflection
will *always* be so many degrees, where the King's or the Queen's
court agrees or not. I understand the State of Ohio once tried to
legislate the value of pi to be 3. It was probably put up to it by a
bunch of optometrists who wanted to make things accurate.
>And Duke-Elder was an ophthalmologist.
But, as I understand it, Prentice was the *culprit*. You say D-E
referred to P's notation in his book. Wasn't P an optometwisted?
>SECOND PART
>
>As I noted before prism grinding is done on almost every lens that has to be
>surfaced by labs like mine or Jeff's..
>
>The following is a simplification. A multifocal lens blank is thick and comes
>with
>parallel surfaces. There is no optical center (OC) yet. Depending on the script
>1. the desired height of the bi(tri) focal seg.
>2. the PD -(inter)pupillary distance of patient.
>3. frame measurements
>4. probably something else I've forgotten here.
>
>All the above enter into how much prism to grind in which direction to put the
>OC
>where it should be.
>
>If all the above comes out perfectly then the lenses have to be blocked
>properly
>for edging to insure that the OC ends up on the patient's face where the doc
>wanted it.
>
>Since this was about prism^ I didn't touch on controlling the thickness of the
>lens. It is tied into the "power" formulae.
>
>My point is that there are lots and lots of formulae to get the desired
>results.
>But the Jeffs will knock them out without too much sweat.
All of which does not justify the unit 'prism diopter' in the
slightest. This unit is simply 1/2 deg and that's it. Why don't you
write an essay on how we should use mudpie = 2*pi, so that we can
write mudpie*r instead of 2*pi*r, thus eliminating the factor 2?
Superfluous units are superfluous units and alchemists using strange
signs are only that. I mean, if you really want to, I guess you could
learn to write in all lower-case letters like jeff, and that would
make things all the more exclusively non-industrial-optics-lab kosher,
right? I mean, who cares about the outside world? If we can get more
$ for genuine *dioptric* stuff, then it must be sorta like
extra-virgin olive oil. Don't want none o' that slightly pregnant
industrial-strength prismatic stuff around, now do we? In fact, we
only use *sterilized* light in our labs (it comes from bugs lights,
you know ;-) )! Or maybe it's *distilled* light -- 200 proof.
That's how we get so high on all that we do. We never even let it
touch human hands until it reaches the caring hands of the boys with
the light touch in the front offices. ;-)))))))))) Yessir! Dirty
ol' degrees would never work for us; we never learned big fractions
like 1/2, and we always wanna abide by royal history anyhow, 'cause it
has culture an' character. Yessir! Ol' Prentice might roll over in
his grave if we started using degrees, but you can bet that, if he
did, he would *never* do it in *degrees* -- only in prismatic
dioperators.
Ray (After a while you've seen all the angles, but it's really cute
how some people manage to get degrees, while still using prism
diopters. They shold all be put in prism.)
Specs31
>It's sorta like that Eleanor Roosevelt quote. After the umpteenth
>time you've seen it, it's sort of a drag.
>
>Ray
DRAG??? ..and Eleanor Roosevelt???...I thought it was J Edgar who liked to
wear garters under his dress....or was that saved for those special occasions,
like when he was spying on the kennedy's doing the hula with a bevy of
babes......
Jeff
Specs31
ray a roni whopped out:
>It goes with out saying -- that you know which direction you want the
>image bent in. If you don't know, you shouldn't bend it in *any*
>direction. You don't have to figure the direction out mathematically
>-- if that's what you're trying to do.
>
>
Not true ray.. did you read the full post?? Dennis knew the number to
multiply a degree to transpose it into a diopter.... but that still will not
give you a direction.....
(my question)
<< > Well... you tell me how to convert degree's to prism diopters?
(his answer)
To convert degrees to prism diopters just multily by 1.7454. >>
I think he grasped the basic math but still didn't understand how it
translates into direction ....
If i just got an RX that said .50 sph. 1D ??...what would that tell me??
need a direction if the degree's are not supplied
>Ho ho ho.<
You and them three Ho's... you get a group discount or what?? I think you may
need more salt peter in your Capt. Crunch in the mornings
>Well, surely the "King of Florida" can proclaim the end of a thread
>and enforce it, right? The next poster to this thread gets thrown to
>the alligators.
Not King yet... the plan has not been put in motion (YET)...and I can post
if I want to... I have the alligators in the jacuzzi out on the deck!! .... and
they don't like nobody other than ... oops then... no make that D'n me...:-)
Jeff
Specs31
scooby doo ray wrote:
>I have to say that I don't really think Jeff was meaning to insult
>people with those "ha ha"s.
Oh yea??... i got your "ha ha" right here buddy...<<grabbing a certian area>>
..:-)
I saw them as just a kind of nervous
>habit. He ought to realize that, in the quantity he used them, they
>became pretty silly after a while though.
They were used on postings by a number of so called non regulars to this
NG... they wouldn't have seen the "nervous tick" you point out... only the
addicted posters would have seen that... Thats why they make that little key
over on the right hand side of your keyboard that has the word "delete" on it..
feel free to use it at any time.....
But he's built upon quite a
>level of independence of just about every outside influence, it seems
>to me.
>
If this was translated into the english version maybe I could reply?? :-)
But then (though them than this that tit for tat) maybe i would just use that
make it disappear button <DELETE>
Gee Ray you almost sounded like you were being half way civil... scared that
Santa is checking up on you?? waiting till the last minute to score brownie
points with the little fat man dressed in red or what???
Or is it possible you just got a little to much of the "nog" mixed in with
the egg nog, and uncle scrooge came by for a visit and you saw the light (which
is refracted on a 170 degree angle over the crossed cylinder and through the
prism its off to grandma's house you go??) :-)
Jeff
>Ray
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
................
>
>thats one thing this group is not short of... long winded
>answers and people who just love to spout off about optics!! :-)
And as they say, always judge a teapot by its spout.
Ray (Teapots in optics? Get a handle on that.)
Raymond A. Chamberlin
spe...@aol.com (Specs31) wrote:
>
............
>
> I figure Ray is just bored and enjoys a good argument.. if any of us said
>white he would say black.....
Well, actually I'd say you're not liable to change Jeff and his
cohorts' minds about the importance of measuring angles in prism
diopters for the purpose of keeping optometry afloat, but hey, look!:
I think we cured Jeff of his "ha ha"s! Hee hee!
Ray